"bent" wrote in message
...
Is there a good chemical for helping to remove a few layers of Minwax
Helmsman Spar Urethane clear Satin finish that may be one to several years
old. For my 20 year old summer pine picnic table. Every other year or so I
scape and sand, sometimes to bare wood on a great portion, but its always
a hassle, iirc the book Understand by Flexner talks about a chemical for
removal of finish like this this and I think the main chemical component
is MEK (methyl ethyl ketone), but I forget the details. I believe it was
said to be unobtainable, but I do think I have seen some form of this
chemical component in a variety of things, like pvc or abs glue for a
guess, and I have always thought of finding out if there is some way to
get me a good stripper for this job one day. Ok, I checked, the "Oatey ABS
Cement" says "Contains Methyl ethyl ketone", and the "Oatey PVC Cement"
says "Contains Methyl ethyl ketone, Tetrahydrofuran, PVC Resin,
Cyclohexanone. I have never tried either of these, and don't know what
would happen. I have tried but anything chemical I have ever tried has
always fallen short of being advantageous, sort of dissolves but can't cut
it. So for the dozenth time I have a cabinet scaper (still can't sharpn
it yet), paint scraper, putty knife, sand paper (by hand and 1/3 sheet
vibration m/c). I have learned over the years that the liquid chlorine
(~$10/ 50L from the pool store) does a good job of bleaching white any of
the bare wood that has darkened, possibly due to water. But its the same
old time-consuming labour grind for the poly prep re&re. I ask now because
all and every of the ~75 sq. ft. of pine pieces are 100% apart, and I have
a chance to make it right between the cracks this the first year ever. So,
any hopes of actually finding some help with the removal via a chemical.


Hello bent,

I appears that you are over analyzing the project. It is really much
more simple than you might think.

1) Clean the table. First, brush off all the loose dirt. Then, use warm,
not hot, water containing Dawn dishwashing liquid, one capful per gallon. I
like Dawn since it has a neutral pH but any dishwashing liquid will work.
Don't saturate the table, use just enough to do the job with clean rags.
Rinse off with fresh water. Again, do not saturate the table. Wipe down to
dry. Now, go over the table with odorless mineral spirits. Use lots of
clean rags. You can saturate the table if you like but it really isn't
necessary. Allow to dry. The purpose of this step is to get the dirt off
the surface that can interfere with penetration of the finish stripper.

2) Apply a good finish stripper. You do not need a caustic stripper. Find
a paste one that has methylene chloride. This is a fast and strong
stripper. Other strippers will either work very slowly or are so corrosive
/ caustic that you might actually damage the wood. Read the ingredients so
you can pick the right one. A very rough rule of thumb is to use the
heaviest one you can find. Methylene chloride is denser than any of the
other organic solvents that are used in finish strippers. It is even more
dense than water. It is also more dense than the waxes used in the paste
strippers. The heaviest can, assuming equal volumes, will probably contain
the most methylene chloride. Apply the stripper with a brush or rag and
don't be stingy with it.

3) After allowing the stripper to sit as per the instructions on the can,
scrape it off. You can use a plastic or metal tool. I like plastic since
it is less likely to accidentally gouge the wood.

4) Without any wiping, apply a second coating of stripper. Let it do its
thing and scrape it off again.

5) Go over the piece with #1 or #2 steel wool or the equivalent ScotchBrite
pad. Saturate the wool or pad with stripper to do this. The idea is to
remove the last traces of finish without scratching the wood to any great
degree. You should go over the whole piece to make sure it is evenly
rubbed.

6) Wipe down the piece with lots of clean rags and then with mineral spirits
to remove any residual wax. I like to use a 1/1/2 (v/v/v) solution of
alcohol / acetone / toluene. This not only removes the wax but it keeps any
residual finish from readhering (sp?) to the piece.

7) Admire your work.

Remember to pay attention to all the safety warnings - lots of
ventilation, no open flames, use gloves, eye protection, etc.

Good luck.