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