Hi all. Rookie woodworker here with a rookie mistake. After gluing and biscuiting my first table top, I had a few seams that were not flush (kinda far off). I used 40 grit sandpaper to sand down the joints and then proceeded up to 400 grit. It felt smooth to the touch and I went ahead and stained and put a coat of polyurethane on. After the poly, the subtle rough edges became very apparent. Is that normal? (ie for a poly to enhance mistakes)

I thought a couple more coats of poly would smooth them out since they are not too deep, but did not do much. Any recommendations? I am not sure if there is a special lacquer that could fill in the scratches, or if I just apply a heavier amount poly and sand out, or just go back to square one and resand to the way it should've been.

Any feedback would be most welcome. Thank you.

On Mon, 22 Jul 2013 22:04:37 -0700 (PDT), djc wrote:

Hi all. Rookie woodworker here with a rookie mistake. After gluing and biscuiting my first table top, I had a few seams that were not flush (kinda far off). I used 40 grit sandpaper to sand down the joints and then proceeded up to 400 grit. It felt smooth to the touch and I went ahead and stained and put a coat of polyurethane on. After the poly, the subtle rough edges became very apparent. Is that normal? (ie for a poly to enhance mistakes)

I thought a couple more coats of poly would smooth them out since they are not too deep, but did not do much. Any recommendations? I am not sure if there is a special lacquer that could fill in the scratches, or if I just apply a heavier amount poly and sand out, or just go back to square one and resand to the way it should've been.

Any feedback would be most welcome. Thank you.

Here's my 2 cents, and remember you get what you paid for. I'm jumping in since
it is almost 1am central time, and nobody else is likely to give you bad advice
this late at night.

If you have an end table, just put a doily on it and no one will notice the
scratches. Table cloth for a dining table, and if it is a coffee table it will
soon be cluttered with magazines and no one can see the defects.

If I had deep, 40 grit scratches, I'd sand down until smooth, doing the entire
top to keep things level. Start with 80 grit and remove all scratches, then go
to 120 then 180. You could go as high as 220, but a lot of folks here on the
wREC seem to think that is plenty when top coating with PU. If the scratches
are in the 120 grit range, I'd be tempted to let the top cure for a few days,
then sand 120-180-220 and try another coat. Using PU as a grain filler is not
what it was designed for and will probably end up looking like a piece of
plastic.

Some of the experts will chime in later today. FWIW, make yourself some cauls
for the next table top, buy lots of clamps and see if you can get a straighter
glueup to reduce sanding. I used to use a belt sander, but frankly, I'm not
very good with it and tend to leave gouges in the wood using one. I do better
with hand planes and scrapers. In a moment of weakness a few months ago, I
bought a Performax 16/32 at an estate sale, but have not needed it yet.

Before you start finishing again, set up a bright light almost horizontal to the
table top and look very closely for any defects. A raking light will make them
show up well. Use the light from all directions. If you can see or feel a
defect, it will almost certainly show up int he finished product. Fix every
defect you find before you start applying finish. Make that last sentence into a
chant for all your future finishing.

Welcome to the group, and don't do anything until Lew, Swing, Leon and some of
the other much more experienced folks (who do this for a living, not a hobby)
can weigh in.

Someone will surely suggest Plastic Wood and yellow paint, but I won't. Where
is Joat when we need him?

Regards,
Roy

On Tuesday, July 23, 2013 12:04:37 AM UTC-5, djc wrote:
Hi all. Rookie woodworker here with a rookie mistake. After gluing and biscuiting my first table top, I had a few seams that were not flush (kinda far off). I used 40 grit sandpaper to sand down the joints and then proceeded up to 400 grit. It felt smooth to the touch and I went ahead and stained and put a coat of polyurethane on. After the poly, the subtle rough edges became very apparent. Is that normal? (ie for a poly to enhance mistakes)



I thought a couple more coats of poly would smooth them out since they are not too deep, but did not do much. Any recommendations? I am not sure if there is a special lacquer that could fill in the scratches, or if I just apply a heavier amount poly and sand out, or just go back to square one and resand to the way it should've been.



Any feedback would be most welcome. Thank you.

I'll add a penny's worth: After I glue up a table top, I take it to the local lumber yard and have them run it through their wide belt sander at 80 grit. I get a much better result in 10 minutes on their machine than a couple of hours of hand work in my shop for less than $10.

Larry

djc wrote:

Hi all. Rookie woodworker here with a rookie mistake. After gluing and
biscuiting my first table top, I had a few seams that were not flush
(kinda far off). I used 40 grit sandpaper to sand down the joints and then
proceeded up to 400 grit. It felt smooth to the touch and I went ahead and
stained and put a coat of polyurethane on. After the poly, the subtle
rough edges became very apparent. Is that normal? (ie for a poly to
enhance mistakes)

I thought a couple more coats of poly would smooth them out since they
are
not too deep, but did not do much. Any recommendations? I am not sure if
there is a special lacquer that could fill in the scratches, or if I just
apply a heavier amount poly and sand out, or just go back to square one
and resand to the way it should've been.

Any feedback would be most welcome. Thank you.

To follow on from Ray. When clamping ALWAYS use the "over/under
alternating clamp" method. In other words, put your first clamp on top,
your second one under, the third on top, etc. Watch you tension and keep an
eye out for any warping of of the joints or bowing of the piece. That will
produce a very flat work piece.

I just finished gluing two panels, and am working on a third, 3/8 x 11 x
144" using this method and have three flat panels. The fun will begin with
I glue those three together, after running them through the planer. But the
same method will produce the same results..

Also, after your final pass with the sander, whether 200 grit or higher,
wipe the piece with Naptha and view it in a raking light. The Naptha will
make your scratches AND and glue show up very plainly. It also dries very
quickly and does not raise the grain.

Deb

On 7/23/2013 6:58 AM, Dr. Deb wrote:
I just finished gluing two panels, and am working on a third, 3/8 x 11 x
144"

Is this typed correctly? You glued up panels 11" x 12 feet? What's the
intended use?

On 7/23/2013 12:04 AM, djc wrote:
Hi all. Rookie woodworker here with a rookie mistake. After gluing and biscuiting my first table top, I had a few seams that were not flush (kinda far off). I used 40 grit sandpaper to sand down the joints and then proceeded up to 400 grit. It felt smooth to the touch and I went ahead and stained and put a coat of polyurethane on. After the poly, the subtle rough edges became very apparent. Is that normal? (ie for a poly to enhance mistakes)

I thought a couple more coats of poly would smooth them out since they are not too deep, but did not do much. Any recommendations? I am not sure if there is a special lacquer that could fill in the scratches, or if I just apply a heavier amount poly and sand out, or just go back to square one and resand to the way it should've been.

Any feedback would be most welcome. Thank you.



The question to ask is, when you went through 40 grit to 400 grit did
you progress through all the grits with out skipping a grit?

Did you wipe down the surface between grits to insure that no grit was
left behind from the previous?

If you skipped grits, actually you can normally skip "1" grit, you have
not removed the previous grits scratch marks.

And FWIW you can normally stop sanding at 180 or 220 when applying poly.

"djc" wrote:

Hi all. Rookie woodworker here with a rookie mistake. After gluing
and biscuiting my first table top, I had a few seams that were not
flush (kinda far off). I used 40 grit sandpaper to sand down the
joints and then proceeded up to 400 grit. It felt smooth to the touch
and I went ahead and stained and put a coat of polyurethane on. After
the poly, the subtle rough edges became very apparent. Is that
normal? (ie for a poly to enhance mistakes)

I thought a couple more coats of poly would smooth them out since they
are not too deep, but did not do much. Any recommendations? I am not
sure if there is a special lacquer that could fill in the scratches,
or if I just apply a heavier amount poly and sand out, or just go back
to square one and resand to the way it should've been.

------------------------------------------------------------
Sounds like in the process of sanding down the joints you now have a
top that is no longer flat.

If so, the only solution is to re-sand the top FLAT and then finish.

Without access to a drum sander, the lowest cost approach is to use a
fairing board and a fairing batten to get a level surface.

You can build a fairing board by getting a mason's wooden float and
replacing the board with a piece of 3/4" plywood that is 4-1/2" wide x
22" long.

You now cut a 9" x 11" sheet of sand paper into two (2), 4-1/2" wide x
11" pieces and attach to the plywood with rubber cement.

While you are getting the mason's float, buy a 3/4" x 3/4" x 1/16" x
96" aluminum angle which will be used as a fairing batten.

Start with 80 grit and sand at +45 degree bias to the long dimension
of the top.

Check your work frequently using the knife edge of the aluminum angle
against the work surface.

If you rub the angle against the work surface, it will leave black
aluminum oxide marks across the high spots showing you where to sand.

When your arms feel like they want to fall off, your top is flat
Grin.

Seriously, you can probably get the top flat and smooth in 3-4 hours
depending on top size.

Once you are satisfied that the top is flat and smooth, change to 100
grit and sand at a -45 degree bias just until are the 80 grit marks
are gone.

A hand held light can help here.

Once you are satisfied the 80 grit marks are gone, change to 150 grit
and sand on +45 degree bias until 100 grit marks are gone.

Keep increasing grit (220, 320, 400) and alternating bias until you
are satisfied.

Sounds a lot more complex than it actually is.

Took 4 years, but faired out a 55 ft sailboat hull using the above
method.

Have fun.

Lew

Leon wrote:
On 7/23/2013 12:04 AM, djc wrote:
Hi all. Rookie woodworker here with a rookie mistake. After gluing
and biscuiting my first table top, I had a few seams that were not
flush (kinda far off). I used 40 grit sandpaper to sand down the
joints and then proceeded up to 400 grit. It felt smooth to the
touch and I went ahead and stained and put a coat of polyurethane
on. After the poly, the subtle rough edges became very apparent. Is
that normal? (ie for a poly to enhance mistakes) I thought a couple
more coats of poly would smooth them out since
they are not too deep, but did not do much. Any recommendations? I
am not sure if there is a special lacquer that could fill in the
scratches, or if I just apply a heavier amount poly and sand out, or
just go back to square one and resand to the way it should've been. Any
feedback would be most welcome. Thank you.



The question to ask is, when you went through 40 grit to 400 grit did
you progress through all the grits with out skipping a grit?

Did you wipe down the surface between grits to insure that no grit was
left behind from the previous?

If you skipped grits, actually you can normally skip "1" grit, you
have not removed the previous grits scratch marks.


I concur with Leon. If you're using a random orbital sander, you can easily
skip a grit, but it you're sanding by hand you have to much more careful in
doing so. 40 grit is some fierce stuff though. I'm not sure I would have
gone that aggressive, but I haven't seen the piece so I can't really say.
Either way - and I have seen your follow up post about the scratch marks
showing in the poly - I suggest you just step back to 220 grit and hit the
whole top. See what that leaves you. If that gets rid of all of the errant
scratches, then you don't need to go any finer. Just proceed to your poly.


And FWIW you can normally stop sanding at 180 or 220 when applying
poly.

Agreed. Automotive base coats, which are a fraction of the viscosity of
poly, will fill 500 grit scratches, so maybe that gives you a perspective on
how fine to go (or not go...) with woodworking finishes.

--

-Mike-

Thank you all for the feedback!
It is great to have so many knowledgeable people share their thoughts and experience. When I used the 40 grit, I was using a belt sander and then switched to an orbital. My main issue was that I switched straight from 40 to 120 grit. I should've added at least one other grit in between. Now I know!

Would anyone recommend adding a filler on top of the PU to fill in the scratches, or is resanding really the only way? Also, what are the consequences of sanding on wood that already has a couple coats of PU?

Thanks again!

Hi Larry. Thanks for advise. What is interesting, I never thought of this idea before, but after reading your post, I passed my local lumber yard today and they had a sign out that I never noticed before, which advertises mill work. Weird coincidence or am I now just aware about mill work, I'm not sure! Thanks again.
Dan

On Tue, 23 Jul 2013 18:56:48 -0700 (PDT), djc1287
wrote:

Thank you all for the feedback!
It is great to have so many knowledgeable people share their thoughts and experience. When I used the 40 grit, I was using a belt sander and then switched to an orbital. My main issue was that I switched straight from 40 to 120 grit. I should've added at least one other grit in between. Now I know!

Would anyone recommend adding a filler on top of the PU to fill in the scratches, or is resanding really the only way? Also, what are the consequences of sanding on wood that already has a couple coats of PU?

Thanks again!

My Dad used to harp at me if I was going to do something, I might as well do it
right. If the table is going to be out where people will see it, and you want
to proudly tell them you built it, then I think you need to resand it.

Chalk this up to a learning experience, and stop in here to read the messages
three or four times a week. This is a great place to ask for advice BEFORE ****
happens.

If you live anywhere near Houston, come over to the house and we'll try out the
wide sander or a couple of hand planes on your top. Somebody else suggested
getting it sanded at a cabinet shop for little money. A good deal if you value
your time at more than $5 per hour.

Good luck with your project, and post pictures on
alt.binaries.pictures.woodworking. Post as regular jpg file, no Yenc. Many
regulars here don't have software to decode Yenc.

Regards,
Roy

"djc1287" wrote:

Would anyone recommend adding a filler on top of the PU to fill in
the scratches, or is resanding really the only way? Also, what are
the consequences of sanding on wood that already has a couple coats
of PU?
---------------------------------------------------------------------------------------
Somehow I think you already know the answer to your question. grin

BTW, if your local lumber yard has a drum sander and will sand your
top for a few $, that's definitely the way to go.

I had a drum sanding shop within about 10 miles which made life easy;
however, looks like he died and the shop was closed since last I used
him.

Never thought about a lumber yard for this contract service.

Guess I'll have to start looking.

Thanks.

Good luck.

Lew

It sounds like the consensus is I can't take a shortcut to fix the problem. Heck, if I didn't try to take a shortcut in the first place, I wouldn't be in this situation! Good lesson to learn early I guess.
Unfortunately, I am in the Seattle area so I won't be able to swing by to learn first hand. I greatly appreciate the offer. I'll post some pics when I finally finish it.
Thank you again.

Dan

wrote:

It sounds like the consensus is I can't take a shortcut to fix the
problem. Heck, if I didn't try to take a shortcut in the first place,
I wouldn't be in this situation! Good lesson to learn early I guess.
Unfortunately, I am in the Seattle area so I won't be able to swing
by to learn first hand. I greatly appreciate the offer. I'll post
some pics when I finally finish it.
Thank you again.
--------------------------------------------------------------------
Just finished rereading an earlier post where you indicate you had a
40 grit belt on a belt sander.

That tells me all I need to know.

There is no way in hell your top is flat and smooth after a visit from
a belt sander.

The only way to get a fair" surface after a belt sander visit is to
use a fairing board, fairing batten and a considerable amout of SWEAT
as outlined in a previous post.

You very quickly learn that a belt sander is an abrasive cutting tool,
NOT a finishing tool.

If you go over to abpw, I'll post a JPEG you might enjoy.

Lew

djc1287 wrote:
Thank you all for the feedback!
It is great to have so many knowledgeable people share their thoughts
and experience. When I used the 40 grit, I was using a belt sander
and then switched to an orbital. My main issue was that I switched
straight from 40 to 120 grit. I should've added at least one other
grit in between. Now I know!


Yeah - that's a bit of a jump. But - you're not the first person to make
that kind of leap. Now, you're in good company.


Would anyone recommend adding a filler on top of the PU to fill in
the scratches, or is resanding really the only way? Also, what are
the consequences of sanding on wood that already has a couple coats
of PU?


Nope. Do it the right way and sand it out. It has been recommended to find
a place local to you that will run it through a sander for you - that's
probably your best bet.

--

-Mike-

On 7/23/2013 8:56 PM, djc1287 wrote:
Thank you all for the feedback!
It is great to have so many knowledgeable people share their thoughts and experience. When I used the 40 grit, I was using a belt sander and then switched to an orbital. My main issue was that I switched straight from 40 to 120 grit. I should've added at least one other grit in between. Now I know!



Keep in mind the size of the scratch, the smaller the scratch the harder
it is to see. Basically It is more important to not skip grit steps
when starting with 40. It tends to be more acceptable to skip a grit
when getting into the finer scratch patterns.

In article ,
djc1287 wrote:

I switched straight from 40 to 120 grit.

40-60-80-100-120

But I would have started at 80...

--
Outside of a dog, a book is man's best friend. Inside a dog, it's too dark to
read. - Groucho Marx