Setting plaster causing wood to warp.
 

I have fitted a 150 x 20mm piece of engineered oak plank vertically
behind a worktop. (The long axis of 800mm is horizontal.) It is fixed
well along the worktop but cannot easily be fixed to the non-flat,
non-vertical wall behind it. I therefore thought it would be a good
idea to put some plaster behind it, both for neatness (a difficult gap
to keep clean) and for support. I used one coat plaster up to 4/5 of
the top of the wooden upstand. Much to my shock, by the next day it had
warped 6mm out of the vertical, and away from the wall at the top. The
bottom is firmly clamped. At first I thought it was a mechanical effect
of the weight of plaster (though on reflection this should not be enough
to bend it) but on closer inspection the top of the plaster is now 5mm
away from the wood. There is some evidence of longitudinal warping,
although it only amounts to 1mm in 800 mm, because it is pretty well
clamped against the worktop.


So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly. Is this a known effect of
plaster? Would waterproofing the wood first have prevented it? Will
it un-warp in time and is there any way I can encourage it to?

Many thanks for any comments.

--

Roger Hayter

Setting plaster causing wood to warp.
 

(Roger Hayter) Wrote in message:
I have fitted a 150 x 20mm piece of engineered oak plank vertically
behind a worktop. (The long axis of 800mm is horizontal.) It is fixed
well along the worktop but cannot easily be fixed to the non-flat,
non-vertical wall behind it. I therefore thought it would be a good
idea to put some plaster behind it, both for neatness (a difficult gap
to keep clean) and for support. I used one coat plaster up to 4/5 of
the top of the wooden upstand. Much to my shock, by the next day it had
warped 6mm out of the vertical, and away from the wall at the top. The
bottom is firmly clamped. At first I thought it was a mechanical effect
of the weight of plaster (though on reflection this should not be enough
to bend it) but on closer inspection the top of the plaster is now 5mm
away from the wood. There is some evidence of longitudinal warping,
although it only amounts to 1mm in 800 mm, because it is pretty well
clamped against the worktop.


So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly. Is this a known effect of
plaster? Would waterproofing the wood first have prevented it? Will
it un-warp in time and is there any way I can encourage it to?

Many thanks for any comments.


Let it dry out before you decide to rip it off. Chances are it
will recover in a few weeks as long as environs are dry &
warm.

Next time (if any) use an adhesive & deal with gaps etc afterwards?
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Setting plaster causing wood to warp.
 

On Wednesday, 22 November 2017 22:44:46 UTC, Roger Hayter wrote:
I have fitted a 150 x 20mm piece of engineered oak plank vertically
behind a worktop. (The long axis of 800mm is horizontal.) It is fixed
well along the worktop but cannot easily be fixed to the non-flat,
non-vertical wall behind it. I therefore thought it would be a good
idea to put some plaster behind it, both for neatness (a difficult gap
to keep clean) and for support. I used one coat plaster up to 4/5 of
the top of the wooden upstand. Much to my shock, by the next day it had
warped 6mm out of the vertical, and away from the wall at the top. The
bottom is firmly clamped. At first I thought it was a mechanical effect
of the weight of plaster (though on reflection this should not be enough
to bend it) but on closer inspection the top of the plaster is now 5mm
away from the wood. There is some evidence of longitudinal warping,
although it only amounts to 1mm in 800 mm, because it is pretty well
clamped against the worktop.


So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly. Is this a known effect of
plaster? Would waterproofing the wood first have prevented it? Will
it un-warp in time and is there any way I can encourage it to?

Many thanks for any comments.

Real wood wouldn't have done that, and it's cheaper.


NT

Setting plaster causing wood to warp.
 

On 23/11/17 03:41, wrote:
On Wednesday, 22 November 2017 22:44:46 UTC, Roger Hayter wrote:
I have fitted a 150 x 20mm piece of engineered oak plank vertically
behind a worktop. (The long axis of 800mm is horizontal.) It is fixed
well along the worktop but cannot easily be fixed to the non-flat,
non-vertical wall behind it. I therefore thought it would be a good
idea to put some plaster behind it, both for neatness (a difficult gap
to keep clean) and for support. I used one coat plaster up to 4/5 of
the top of the wooden upstand. Much to my shock, by the next day it had
warped 6mm out of the vertical, and away from the wall at the top. The
bottom is firmly clamped. At first I thought it was a mechanical effect
of the weight of plaster (though on reflection this should not be enough
to bend it) but on closer inspection the top of the plaster is now 5mm
away from the wood. There is some evidence of longitudinal warping,
although it only amounts to 1mm in 800 mm, because it is pretty well
clamped against the worktop.


So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly. Is this a known effect of
plaster? Would waterproofing the wood first have prevented it? Will
it un-warp in time and is there any way I can encourage it to?

Many thanks for any comments.

Real wood wouldn't have done that, and it's cheaper.



real wood would have dione worse than that

NT



--
New Socialism consists essentially in being seen to have your heart in
the right place whilst your head is in the clouds and your hand is in
someone else's pocket.

Setting plaster causing wood to warp.
 

On 22/11/17 22:44, Roger Hayter wrote:
I have fitted a 150 x 20mm piece of engineered oak plank vertically
behind a worktop. (The long axis of 800mm is horizontal.) It is fixed
well along the worktop but cannot easily be fixed to the non-flat,
non-vertical wall behind it. I therefore thought it would be a good
idea to put some plaster behind it, both for neatness (a difficult gap
to keep clean) and for support. I used one coat plaster up to 4/5 of
the top of the wooden upstand. Much to my shock, by the next day it had
warped 6mm out of the vertical, and away from the wall at the top. The
bottom is firmly clamped. At first I thought it was a mechanical effect
of the weight of plaster (though on reflection this should not be enough
to bend it) but on closer inspection the top of the plaster is now 5mm
away from the wood. There is some evidence of longitudinal warping,
although it only amounts to 1mm in 800 mm, because it is pretty well
clamped against the worktop.


So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly. Is this a known effect of
plaster? Would waterproofing the wood first have prevented it? Will
it un-warp in time and is there any way I can encourage it to?

Many thanks for any comments.


Yes oak warps if wet. I had it happen to me. So next time, I would tape
the back of the wood to keep the water from the plaster going in.

Setting plaster causing wood to warp.
 

On 23/11/17 00:20, jim wrote:
(Roger Hayter) Wrote in message:
I have fitted a 150 x 20mm piece of engineered oak plank vertically
behind a worktop. (The long axis of 800mm is horizontal.) It is fixed
well along the worktop but cannot easily be fixed to the non-flat,
non-vertical wall behind it. I therefore thought it would be a good
idea to put some plaster behind it, both for neatness (a difficult gap
to keep clean) and for support. I used one coat plaster up to 4/5 of
the top of the wooden upstand. Much to my shock, by the next day it had
warped 6mm out of the vertical, and away from the wall at the top. The
bottom is firmly clamped. At first I thought it was a mechanical effect
of the weight of plaster (though on reflection this should not be enough
to bend it) but on closer inspection the top of the plaster is now 5mm
away from the wood. There is some evidence of longitudinal warping,
although it only amounts to 1mm in 800 mm, because it is pretty well
clamped against the worktop.


So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly. Is this a known effect of
plaster? Would waterproofing the wood first have prevented it? Will
it un-warp in time and is there any way I can encourage it to?

Many thanks for any comments.


Let it dry out before you decide to rip it off. Chances are it
will recover in a few weeks as long as environs are dry &
warm.

Next time (if any) use an adhesive & deal with gaps etc afterwards?


Engineered might. Solid oak won't.

Setting plaster causing wood to warp.
 

The Natural Philosopher Wrote in message:
On 23/11/17 03:41, wrote:
On Wednesday, 22 November 2017 22:44:46 UTC, Roger Hayter wrote:
I have fitted a 150 x 20mm piece of engineered oak plank vertically
behind a worktop. (The long axis of 800mm is horizontal.) It is fixed
well along the worktop but cannot easily be fixed to the non-flat,
non-vertical wall behind it. I therefore thought it would be a good
idea to put some plaster behind it, both for neatness (a difficult gap
to keep clean) and for support. I used one coat plaster up to 4/5 of
the top of the wooden upstand. Much to my shock, by the next day it had
warped 6mm out of the vertical, and away from the wall at the top. The
bottom is firmly clamped. At first I thought it was a mechanical effect
of the weight of plaster (though on reflection this should not be enough
to bend it) but on closer inspection the top of the plaster is now 5mm
away from the wood. There is some evidence of longitudinal warping,
although it only amounts to 1mm in 800 mm, because it is pretty well
clamped against the worktop.


So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly. Is this a known effect of
plaster? Would waterproofing the wood first have prevented it? Will
it un-warp in time and is there any way I can encourage it to?

Many thanks for any comments.

Real wood wouldn't have done that, and it's cheaper.



real wood would have dione worse than that

+1

--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Setting plaster causing wood to warp.
 

On 23/11/17 07:40, Tim Watts wrote:
On 23/11/17 00:20, jim wrote:
(Roger Hayter) Wrote in message:
I have fitted aÂ* 150 x 20mm piece of engineered oak plank vertically
behind a worktop. (The long axis of 800mm is horizontal.)Â* It is fixed
well along the worktop but cannot easily be fixed to the non-flat,
non-vertical wall behind it.Â*Â* I therefore thought it would be a good
idea to put some plaster behind it, both for neatness (a difficult gap
to keep clean) and for support.Â* I used one coat plaster up to 4/5 of
the top of the wooden upstand.Â* Much to my shock, by the next day it had
warped 6mm out of the vertical, and away from the wall at the top.Â* The
bottom is firmly clamped.Â* At first I thought it was a mechanical effect
of the weight of plaster (though on reflection this should not be enough
to bend it) but on closer inspection the top of the plaster is now 5mm
away from the wood.Â*Â* There is some evidence of longitudinal warping,
although it only amounts to 1mm in 800 mm, because it is pretty well
clamped against the worktop.


So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly.Â*Â* Is this a known effect of
plaster?Â*Â* Would waterproofing the wood first have prevented it?Â*Â* Will
it un-warp in time and is there any way I can encourage it to?

Many thanks for any comments.


Let it dry out before you decide to rip it off. Chances are it
Â* will recover in a few weeks as long as environs are dry &
Â* warm.

Next time (if any) use an adhesive & deal with gaps etc afterwards?


Engineered might. Solid oak won't.

Wrong (as usual)

summer to winter warping of soild wood is it expands and contracts with
the summer humidoty and teh winter centeral heating is established fact.
Plywood by using diggerent wood grain directions it its lates, is far
less prone, but even ply will warp if one side of it is soaked.


--
Gun Control: The law that ensures that only criminals have guns.

Setting plaster causing wood to warp.
 

On 23/11/2017 07:40, Tim Watts wrote:
On 23/11/17 00:20, jim wrote:
(Roger Hayter) Wrote in message:

So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly.Â*Â* Is this a known effect of
plaster?Â*Â* Would waterproofing the wood first have prevented it?Â*Â* Will
it un-warp in time and is there any way I can encourage it to?

Many thanks for any comments.

It is the dampness and perhaps to some extent the heat of cure coming
from the plaster and goiing into the wood. Wet wood swells up as it
absorbs moisture - some it it is probably reversible but perhaps not
all. It would have been safer to plaster first and then attach the wood
(or remove the wood plaster and let it dry for a couple of weeks).

Pafge 15 of this has the coefficients for guestimating wood dimensional
stability with changes ambient humidity (US timber).

https://www.fpl.fs.fed.us/documnts/f...tr113/ch12.pdf

Let it dry out before you decide to rip it off. Chances are it
Â* will recover in a few weeks as long as environs are dry &
Â* warm.

Next time (if any) use an adhesive & deal with gaps etc afterwards?

Engineered might. Solid oak won't.

Seasoned solid oak won't but green worked oak will change dimensions a
bit as it dries - especially if as is common it is used as a mantle
piece above a wood burning stove where it gets nice and warm.
Dimensional stability of wood with humidity is interesting.

Even so I wouldn't want to risk it without putting a layer of oil on the
wood to protect it first. Any trace of iron in the water and you get
nasty black tannin stains going into the previously clean wood.

--
Regards,
Martin Brown

Setting plaster causing wood to warp.
 

On Wed, 22 Nov 2017 22:44:43 +0000, (Roger Hayter) wrote:

Is this a known effect of
plaster?

Of the water, yes...

Would waterproofing the wood first have prevented it?

Probably.

Will it un-warp in time

probalby....

and is there any way I can encourage it to?

You could wet the front, which would cause it to warp the other way.

Best to very firmly do nothing for a few weeks, though, and then see.


Thomas Prufer

Setting plaster causing wood to warp.
 

On Wed, 22 Nov 2017 22:44:43 +0000
(Roger Hayter) wrote:

I have fitted a 150 x 20mm piece of engineered oak plank vertically
behind a worktop. (The long axis of 800mm is horizontal.) It is fixed
well along the worktop but cannot easily be fixed to the non-flat,
non-vertical wall behind it. I therefore thought it would be a good
idea to put some plaster behind it, both for neatness (a difficult gap
to keep clean) and for support. I used one coat plaster up to 4/5 of
the top of the wooden upstand. Much to my shock, by the next day it
had warped 6mm out of the vertical, and away from the wall at the
top. The bottom is firmly clamped. At first I thought it was a
mechanical effect of the weight of plaster (though on reflection this
should not be enough to bend it) but on closer inspection the top of
the plaster is now 5mm away from the wood. There is some evidence
of longitudinal warping, although it only amounts to 1mm in 800 mm,
because it is pretty well clamped against the worktop.


So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly. Is this a known effect of
plaster? Would waterproofing the wood first have prevented it?
Will it un-warp in time and is there any way I can encourage it to?

Many thanks for any comments.



If you're going to have another go at it use car body filler instead of
plaster. Or fill the bulk of the gap with expanding foam and leave just
the last few mm to be filled with plaster to minimise the wetting.

Setting plaster causing wood to warp.
 

Steve wrote:

On Wed, 22 Nov 2017 22:44:43 +0000
(Roger Hayter) wrote:

I have fitted a 150 x 20mm piece of engineered oak plank vertically
behind a worktop. (The long axis of 800mm is horizontal.) It is fixed
well along the worktop but cannot easily be fixed to the non-flat,
non-vertical wall behind it. I therefore thought it would be a good
idea to put some plaster behind it, both for neatness (a difficult gap
to keep clean) and for support. I used one coat plaster up to 4/5 of
the top of the wooden upstand. Much to my shock, by the next day it
had warped 6mm out of the vertical, and away from the wall at the
top. The bottom is firmly clamped. At first I thought it was a
mechanical effect of the weight of plaster (though on reflection this
should not be enough to bend it) but on closer inspection the top of
the plaster is now 5mm away from the wood. There is some evidence
of longitudinal warping, although it only amounts to 1mm in 800 mm,
because it is pretty well clamped against the worktop.


So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly. Is this a known effect of
plaster? Would waterproofing the wood first have prevented it?
Will it un-warp in time and is there any way I can encourage it to?

Many thanks for any comments.



If you're going to have another go at it use car body filler instead of
plaster. Or fill the bulk of the gap with expanding foam and leave just
the last few mm to be filled with plaster to minimise the wetting.

Thanks for the useful advice, and to everyone else who has confirmed my
error. I just didn't realise the wood would absorb water so fast.

I am definitely not going to do it again, but will try to remember to
report back in a few weeks if there has been any improvement.




--

Roger Hayter

Setting plaster causing wood to warp.
 

On 22/11/2017 22:44, Roger Hayter wrote:
I have fitted a 150 x 20mm piece of engineered oak plank vertically
behind a worktop. (The long axis of 800mm is horizontal.) It is fixed
well along the worktop but cannot easily be fixed to the non-flat,
non-vertical wall behind it. I therefore thought it would be a good
idea to put some plaster behind it, both for neatness (a difficult gap
to keep clean) and for support. I used one coat plaster up to 4/5 of
the top of the wooden upstand. Much to my shock, by the next day it had
warped 6mm out of the vertical, and away from the wall at the top. The
bottom is firmly clamped. At first I thought it was a mechanical effect
of the weight of plaster (though on reflection this should not be enough
to bend it) but on closer inspection the top of the plaster is now 5mm
away from the wood. There is some evidence of longitudinal warping,
although it only amounts to 1mm in 800 mm, because it is pretty well
clamped against the worktop.


So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly. Is this a known effect of
plaster? Would waterproofing the wood first have prevented it? Will
it un-warp in time and is there any way I can encourage it to?

The short answer is yes, the dampness from the new plaster would have
been the cause. Chances are as it dries out it will unbend somewhat,
although it might not do it completely. It will also depend a bit on how
much water got through to the oak itself, and whether it was air dried
or kiln dried originally - generally its harder to permanently bend kiln
dried hard woods using steam or moisture.

Engineered planks are interesting things. The addition of the ply to the
back of them, helps reduce the seasonal variation in width (most change
in size of real wood will be across the grain and not along it). Bonding
a thick layer of ply to a relatively thin layer of seasoned oak will
tend to resist that change. However the assumption here is that the ply
side is mostly protected from large changes in humidity, and its the
visible oak face that will see most of those changes. This works well
for a floor, where you don't want your tight fitting boards to shrink
and open up gaps.

In your application its the ply side that got the large increase in
humidity, which being thicker probably caused more pronounced bending
than would have been the case if it were the thinner size that got wet.

Prevention; sealing the back of the board may have helped (although if
the front was not also sealed that may also encourage bending naturally
later if the board was not fully acclimated to the room first)


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Setting plaster causing wood to warp.
 

On 23/11/17 08:02, The Natural Philosopher wrote:

Wrong (as usual)

Not wrong and not as usual. You just can't help sniping, can you?

I said in context, that solid oak won't recovered for wetness related
warping - this is WETNESS from the plaster not humidity.

I also said engineered might recover (but that's just a whole lot of
"depends")

Setting plaster causing wood to warp.
 

On 23/11/17 09:13, Martin Brown wrote:
On 23/11/2017 07:40, Tim Watts wrote:
On 23/11/17 00:20, jim wrote:
(Roger Hayter) Wrote in message:

So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly.Â*Â* Is this a known effect of
plaster?Â*Â* Would waterproofing the wood first have prevented it?Â*Â* Will
it un-warp in time and is there any way I can encourage it to?

Many thanks for any comments.

It is the dampness and perhaps to some extent the heat of cure coming
from the plaster and goiing into the wood. Wet wood swells up as it
absorbs moisture - some it it is probably reversible but perhaps not
all. It would have been safer to plaster first and then attach the wood
(or remove the wood plaster and let it dry for a couple of weeks).

Pafge 15 of this has the coefficients for guestimating wood dimensional
stability with changes ambient humidity (US timber).

https://www.fpl.fs.fed.us/documnts/f...tr113/ch12.pdf

Let it dry out before you decide to rip it off. Chances are it
Â* will recover in a few weeks as long as environs are dry &
Â* warm.

Next time (if any) use an adhesive & deal with gaps etc afterwards?

Engineered might. Solid oak won't.

Seasoned solid oak won't but green worked oak will change dimensions a
bit as it dries - especially if as is common it is used as a mantle
piece above a wood burning stove where it gets nice and warm.
Dimensional stability of wood with humidity is interesting.

Oak also has a tendency to cup if it gets wet - my personal experience
(due to wet plaster) was very dry oak - been dried, been machined, been
inside for a while.

The cupping was about 1/8" in 8" - I managed to sand/plane most of it
flat in situ.

But oak is known as being a more of a bugger for wet related
warping/cupping than other species commonly found in a house.


Even so I wouldn't want to risk it without putting a layer of oil on the
wood to protect it first. Any trace of iron in the water and you get
nasty black tannin stains going into the previously clean wood.

Setting plaster causing wood to warp.
 

On 23/11/17 11:06, Tim Watts wrote:
I said in context, that solid oak won't recovered for wetness related
warping

No, you said it wouldnt have happened at all.


--
Climate Change: Socialism wearing a lab coat.

Setting plaster causing wood to warp.
 

On 23/11/17 11:06, Tim Watts wrote:
On 23/11/17 08:02, The Natural Philosopher wrote:

Wrong (as usual)

Not wrong and not as usual. You just can't help sniping, can you?

I said in context, that solid oak won't recovered for wetness related
warping - this is WETNESS from the plaster not humidity.


Wetenss is humidity you daft plonker!

I also said engineered might recover (but that's just a whole lot of
"depends")

All wood recovers when returned to it's original moisture content.

Engineered or otherwise.

The point is more about the speed of absorption in both types in this case.




--
Climate Change: Socialism wearing a lab coat.

Setting plaster causing wood to warp.
 

On 23/11/17 11:08, Tim Watts wrote:
On 23/11/17 09:13, Martin Brown wrote:
On 23/11/2017 07:40, Tim Watts wrote:
On 23/11/17 00:20, jim wrote:
(Roger Hayter) Wrote in message:

So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly.Â*Â* Is this a known effect of
plaster?Â*Â* Would waterproofing the wood first have prevented it?
Will
it un-warp in time and is there any way I can encourage it to?

Many thanks for any comments.

It is the dampness and perhaps to some extent the heat of cure coming
from the plaster and goiing into the wood. Wet wood swells up as it
absorbs moisture - some it it is probably reversible but perhaps not
all. It would have been safer to plaster first and then attach the
wood (or remove the wood plaster and let it dry for a couple of weeks).

Pafge 15 of this has the coefficients for guestimating wood
dimensional stability with changes ambient humidity (US timber).

https://www.fpl.fs.fed.us/documnts/f...tr113/ch12.pdf

Let it dry out before you decide to rip it off. Chances are it
Â* will recover in a few weeks as long as environs are dry &
Â* warm.

Next time (if any) use an adhesive & deal with gaps etc afterwards?

Engineered might. Solid oak won't.

Seasoned solid oak won't but green worked oak will change dimensions a
bit as it dries - especially if as is common it is used as a mantle
piece above a wood burning stove where it gets nice and warm.
Dimensional stability of wood with humidity is interesting.

Oak also has a tendency to cup if it gets wet - my personal experience
(due to wet plaster) was very dry oak - been dried, been machined, been
inside for a while.


sigh. All wood has a tendencey to cup if its cut tangentially to the
tree trunk surface. Only 4 planks will not cup when cut from a
quaetersawn trunk.



The cupping was about 1/8" in 8" - I managed to sand/plane most of it
flat in situ.

But oak is known as being a more of a bugger for wet related
warping/cupping than other species commonly found in a house.

No, it isn't.

In fact wood expansion between humidity or 'wetness' changes is fairly
constant amongst all species.

It's just that you dont normally have pine or other softwoods exposed
where you can look at them. Pine is a complate **** for warping.
largelry because its cut from smaller boles and so teh graon goes in
every which direction across the planks.

And where you are showing oak, you likeley want to see the open grain
patterns, and that means tangential sawn raher than quarter sawn.

Tangential sawn always cups on humidity change (wetness) since shrinkage
from green is alwayts greater tangential to the surface of the wood,
rather than radially towards the heart wood. Thats why sawn logs dry out
with radial cracks


ratio of longitudinal shrinkage (the height of the tree) to radial to
tangential is IIRC about 1:3:10.


--
In todays liberal progressive conflict-free education system, everyone
gets full Marx.

Setting plaster causing wood to warp.
 

On 23/11/17 11:30, The Natural Philosopher wrote:
On 23/11/17 11:06, Tim Watts wrote:
I said in context, that solid oak won't recovered for wetness related
warping

No, you said it wouldnt have happened at all.



No I didn't.

Setting plaster causing wood to warp.
 

On 23/11/17 11:33, The Natural Philosopher wrote:
On 23/11/17 11:06, Tim Watts wrote:
On 23/11/17 08:02, The Natural Philosopher wrote:

Wrong (as usual)

Not wrong and not as usual. You just can't help sniping, can you?

I said in context, that solid oak won't recovered for wetness related
warping - this is WETNESS from the plaster not humidity.


Wetenss is humidity you daft plonker!

Don't call me a plonker, especially if you are talking crap.

Wetness implies liquid water.

Humidity is gaseous water.

Setting plaster causing wood to warp.
 

On 23/11/17 13:08, Tim Watts wrote:
On 23/11/17 11:33, The Natural Philosopher wrote:
On 23/11/17 11:06, Tim Watts wrote:
On 23/11/17 08:02, The Natural Philosopher wrote:

Wrong (as usual)

Not wrong and not as usual. You just can't help sniping, can you?

I said in context, that solid oak won't recovered for wetness related
warping - this is WETNESS from the plaster not humidity.


Wetenss is humidity you daft plonker!

Don't call me a plonker, especially if you are talking crap.

Wetness implies liquid water.

Humidity is gaseous water.

So gaseous water isnt wet?


--
€œA leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
€œWe did this ourselves.€�

ۥ Lao Tzu, Tao Te Ching

Setting plaster causing wood to warp.
 

On Thu, 23 Nov 2017 10:15:13 +0000
(Roger Hayter) wrote:

Steve wrote:

On Wed, 22 Nov 2017 22:44:43 +0000
(Roger Hayter) wrote:

I have fitted a 150 x 20mm piece of engineered oak plank
vertically behind a worktop. (The long axis of 800mm is
horizontal.) It is fixed well along the worktop but cannot
easily be fixed to the non-flat, non-vertical wall behind it. I
therefore thought it would be a good idea to put some plaster
behind it, both for neatness (a difficult gap to keep clean) and
for support. I used one coat plaster up to 4/5 of the top of the
wooden upstand. Much to my shock, by the next day it had warped
6mm out of the vertical, and away from the wall at the top. The
bottom is firmly clamped. At first I thought it was a mechanical
effect of the weight of plaster (though on reflection this should
not be enough to bend it) but on closer inspection the top of the
plaster is now 5mm away from the wood. There is some evidence
of longitudinal warping, although it only amounts to 1mm in 800
mm, because it is pretty well clamped against the worktop.


So clearly the side of the engineered wood blocks in contact with
the plaster has expanded very significantly. Is this a known
effect of plaster? Would waterproofing the wood first have
prevented it? Will it un-warp in time and is there any way I can
encourage it to?

Many thanks for any comments.



If you're going to have another go at it use car body filler
instead of plaster. Or fill the bulk of the gap with expanding foam
and leave just the last few mm to be filled with plaster to
minimise the wetting.

Thanks for the useful advice, and to everyone else who has confirmed
my error. I just didn't realise the wood would absorb water so
fast.

I am definitely not going to do it again, but will try to remember to
report back in a few weeks if there has been any improvement.


Did the plaster sink and so fill the void left by the timber warping?

If so, I can't see how it could dry back to straight.

If you wrapped the timber in clingfilm would it be possible to remove
it after the plaster set?

Else, shrug; say it's rustic shabby chic.

Setting plaster causing wood to warp.
 

On 23/11/2017 11:33, The Natural Philosopher wrote:
On 23/11/17 11:06, Tim Watts wrote:

I also said engineered might recover (but that's just a whole lot of
"depends")

All wood recovers when returned to it's original moisture content.

********!

Dry some green oak and then try and get it back to its original shape -
not going to happen no matter how wet you get it.

Oak in particular behaves very differently depending on how it was
seasoned. Kiln dried stuff be less likely to distort in high humidity
than naturally dried stuff.

Engineered or otherwise.

The point is more about the speed of absorption in both types in this case.

The direction of the bend in the OPs case would suggest it was the ply
swelling that was causing most of the movement.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
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| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Setting plaster causing wood to warp.
 

Steve wrote:

On Thu, 23 Nov 2017 10:15:13 +0000
(Roger Hayter) wrote:

Steve wrote:

On Wed, 22 Nov 2017 22:44:43 +0000
(Roger Hayter) wrote:

I have fitted a 150 x 20mm piece of engineered oak plank
vertically behind a worktop. (The long axis of 800mm is
horizontal.) It is fixed well along the worktop but cannot
easily be fixed to the non-flat, non-vertical wall behind it. I
therefore thought it would be a good idea to put some plaster
behind it, both for neatness (a difficult gap to keep clean) and
for support. I used one coat plaster up to 4/5 of the top of the
wooden upstand. Much to my shock, by the next day it had warped
6mm out of the vertical, and away from the wall at the top. The
bottom is firmly clamped. At first I thought it was a mechanical
effect of the weight of plaster (though on reflection this should
not be enough to bend it) but on closer inspection the top of the
plaster is now 5mm away from the wood. There is some evidence
of longitudinal warping, although it only amounts to 1mm in 800
mm, because it is pretty well clamped against the worktop.


So clearly the side of the engineered wood blocks in contact with
the plaster has expanded very significantly. Is this a known
effect of plaster? Would waterproofing the wood first have
prevented it? Will it un-warp in time and is there any way I can
encourage it to?

Many thanks for any comments.



If you're going to have another go at it use car body filler
instead of plaster. Or fill the bulk of the gap with expanding foam
and leave just the last few mm to be filled with plaster to
minimise the wetting.

Thanks for the useful advice, and to everyone else who has confirmed
my error. I just didn't realise the wood would absorb water so
fast.

I am definitely not going to do it again, but will try to remember to
report back in a few weeks if there has been any improvement.


Did the plaster sink and so fill the void left by the timber warping?

No it didn't actually, a gap appeared between the set plaster and the
wood.



If so, I can't see how it could dry back to straight.

If you wrapped the timber in clingfilm would it be possible to remove
it after the plaster set?
The timber is very securely glued at the bottom edge, so I can't easily
remove it.



Else, shrug; say it's rustic shabby chic.


I think so, it's not important enough to do again, being a removable
replacement for a a fixed worktop that had to be removed destructively
to allow a new oil boiler to be fitted.


--

Roger Hayter

Setting plaster causing wood to warp.
 

John Rumm wrote:

On 23/11/2017 11:33, The Natural Philosopher wrote:
On 23/11/17 11:06, Tim Watts wrote:

I also said engineered might recover (but that's just a whole lot of
"depends")

All wood recovers when returned to it's original moisture content.

********!

Dry some green oak and then try and get it back to its original shape -
not going to happen no matter how wet you get it.

Oak in particular behaves very differently depending on how it was
seasoned. Kiln dried stuff be less likely to distort in high humidity
than naturally dried stuff.

Engineered or otherwise.

The point is more about the speed of absorption in both types in this case.

The direction of the bend in the OPs case would suggest it was the ply
swelling that was causing most of the movement.

Perhaps I was inaccurately calling it engineered oak. In fact it is
made of small blocks compressed and glued together and is the same both
sides. Is that better or worse.


--

Roger Hayter

Setting plaster causing wood to warp.
 

On 23/11/2017 22:14, Roger Hayter wrote:
John Rumm wrote:

The direction of the bend in the OPs case would suggest it was the ply
swelling that was causing most of the movement.

Perhaps I was inaccurately calling it engineered oak. In fact it is
made of small blocks compressed and glued together and is the same both
sides. Is that better or worse.

"Engineered" normally implies a man made board either bonded to one side
or inserted as a core (depends a bit on what you are describing - e.g.
engineered floor will usually be ply on the underside. An engineered
door would be real wood on all the facing sides and MDF or ply in the core.

Are these all oak blocks or is the core made from something different?

(lots of "solid oak" furniture these days is made from reconstituted
boards assembled from lots of small offcuts finger jointed end to end
and then bonded up into laminations)

Either way, blocks will tend to behave differently from solid wood
because the glue between layers will stop the moisture travelling
through the wood in the same way it would with solid. That can make
bending more pronounced when unevenly exposed to moisture since it
concentrates the expansion in the blocks exposed directly to the moisture.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Setting plaster causing wood to warp.
 

On Thu, 23 Nov 2017 13:08:08 +0000
Tim Watts wrote:

On 23/11/17 11:33, The Natural Philosopher wrote:
On 23/11/17 11:06, Tim Watts wrote:
[...]
[...]
[...]

Wetenss is humidity you daft plonker!

Don't call me a plonker, especially if you are talking crap.

Wetness implies liquid water.

Humidity is gaseous water.

Strictly speaking it's vapour, not gas.

Setting plaster causing wood to warp.
 

On Wed, 22 Nov 2017 22:44:43 +0000
(Roger Hayter) wrote:

So clearly the side of the engineered wood blocks in contact with the
plaster has expanded very significantly. Is this a known effect of
plaster?

It's a known effect of water.

Would waterproofing the wood first have prevented it?

Probably mostly - I'd have put polythene between the wood and plaster,
and only fixed the wood after the plaster had cured. Or oiled/waxed
the wood (which would be a good idea in a worktop situation anyway).

Will it un-warp in time and is there any way I can encourage it to?

Probably, but you'll not easily accelerate it - applying heat or using
a dehumidifier will affect the front as well as the back, but you want
a differential effect to correct the curvature. Possibly ignore that
on the basis that the wet from the back will eventually migrate to
the dry at the front, and that may happen quicker than just leaving it
to dry naturally.

Setting plaster causing wood to warp.
 

John Rumm wrote:

On 23/11/2017 22:14, Roger Hayter wrote:
John Rumm wrote:

The direction of the bend in the OPs case would suggest it was the ply
swelling that was causing most of the movement.

Perhaps I was inaccurately calling it engineered oak. In fact it is
made of small blocks compressed and glued together and is the same both
sides. Is that better or worse.

"Engineered" normally implies a man made board either bonded to one side
or inserted as a core (depends a bit on what you are describing - e.g.
engineered floor will usually be ply on the underside. An engineered
door would be real wood on all the facing sides and MDF or ply in the core.

Are these all oak blocks or is the core made from something different?

(lots of "solid oak" furniture these days is made from reconstituted
boards assembled from lots of small offcuts finger jointed end to end
and then bonded up into laminations)

Either way, blocks will tend to behave differently from solid wood
because the glue between layers will stop the moisture travelling
through the wood in the same way it would with solid. That can make
bending more pronounced when unevenly exposed to moisture since it
concentrates the expansion in the blocks exposed directly to the moisture.

Actually I have re-examined the problem and it looks as though there may
be something in my original theory that the plaster may have had a
chemical effect, rather than purely acting as a reservoir of water.
The wooden blocks themselves have hardly warped but the three glued
joints between the blocks have widened on the plaster side from an
imperceptible width before to about 1/2 a millimeter now. This seems a
more destructive effect on the glue than I would expect from plain water
seeing that this wood is sold for kitchen use with only light varnish.

--

Roger Hayter

Setting plaster causing wood to warp.
 

On 26/11/2017 14:33, Roger Hayter wrote:
John Rumm wrote:

On 23/11/2017 22:14, Roger Hayter wrote:
John Rumm wrote:

The direction of the bend in the OPs case would suggest it was the ply
swelling that was causing most of the movement.

Perhaps I was inaccurately calling it engineered oak. In fact it is
made of small blocks compressed and glued together and is the same both
sides. Is that better or worse.

"Engineered" normally implies a man made board either bonded to one side
or inserted as a core (depends a bit on what you are describing - e.g.
engineered floor will usually be ply on the underside. An engineered
door would be real wood on all the facing sides and MDF or ply in the core.

Are these all oak blocks or is the core made from something different?

(lots of "solid oak" furniture these days is made from reconstituted
boards assembled from lots of small offcuts finger jointed end to end
and then bonded up into laminations)

Either way, blocks will tend to behave differently from solid wood
because the glue between layers will stop the moisture travelling
through the wood in the same way it would with solid. That can make
bending more pronounced when unevenly exposed to moisture since it
concentrates the expansion in the blocks exposed directly to the moisture.

Actually I have re-examined the problem and it looks as though there may
be something in my original theory that the plaster may have had a
chemical effect, rather than purely acting as a reservoir of water.
The wooden blocks themselves have hardly warped but the three glued
joints between the blocks have widened on the plaster side from an
imperceptible width before to about 1/2 a millimeter now. This seems a
more destructive effect on the glue than I would expect from plain water
seeing that this wood is sold for kitchen use with only light varnish.

That could equally be the effect of the timber drying out again and
shrinking. If it does that differentially over the thickness then
something splitting is not unexpected.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Setting plaster causing wood to warp.
 

John Rumm wrote:

On 26/11/2017 14:33, Roger Hayter wrote:
snip

Actually I have re-examined the problem and it looks as though there may
be something in my original theory that the plaster may have had a
chemical effect, rather than purely acting as a reservoir of water.
The wooden blocks themselves have hardly warped but the three glued
joints between the blocks have widened on the plaster side from an
imperceptible width before to about 1/2 a millimeter now. This seems a
more destructive effect on the glue than I would expect from plain water
seeing that this wood is sold for kitchen use with only light varnish.

That could equally be the effect of the timber drying out again and
shrinking. If it does that differentially over the thickness then
something splitting is not unexpected.

Good point, I should have looked more carefully when it first happened.

--

Roger Hayter

Setting plaster causing wood to warp.
 

(Roger Hayter) Wrote in message:
John Rumm wrote:

On 26/11/2017 14:33, Roger Hayter wrote:
snip

Actually I have re-examined the problem and it looks as though there may
be something in my original theory that the plaster may have had a
chemical effect, rather than purely acting as a reservoir of water.
The wooden blocks themselves have hardly warped but the three glued
joints between the blocks have widened on the plaster side from an
imperceptible width before to about 1/2 a millimeter now. This seems a
more destructive effect on the glue than I would expect from plain water
seeing that this wood is sold for kitchen use with only light varnish.

That could equally be the effect of the timber drying out again and
shrinking. If it does that differentially over the thickness then
something splitting is not unexpected.

Good point, I should have looked more carefully when it first happened.


Is the whole piece straightening back out any yet?
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Setting plaster causing wood to warp.
 

jim k wrote:

(Roger Hayter) Wrote in message:
John Rumm wrote:

On 26/11/2017 14:33, Roger Hayter wrote:
snip

Actually I have re-examined the problem and it looks as though there may
be something in my original theory that the plaster may have had a
chemical effect, rather than purely acting as a reservoir of water.
The wooden blocks themselves have hardly warped but the three glued
joints between the blocks have widened on the plaster side from an
imperceptible width before to about 1/2 a millimeter now. This seems a
more destructive effect on the glue than I would expect from plain water
seeing that this wood is sold for kitchen use with only light varnish.

That could equally be the effect of the timber drying out again and
shrinking. If it does that differentially over the thickness then
something splitting is not unexpected.

Good point, I should have looked more carefully when it first happened.


Is the whole piece straightening back out any yet?

No. Though it has probably stopped getting worse.The total deflection
is about 8mm in 150mm.

--

Roger Hayter