Expert: Greg Scholl - 10/31/2010

Question
QUESTION: Our table my wife and I purchased about 2 years ago began to have its finish flake and peel just weeks after buying it. The store wouldn't take it back, so we had to live with it.  We applied some poly coats to it, but ultimately the table began to get worse and worse as time went on.

So (this week) I decided that I would just sand the finish off all the way back down to the grain and reapply a finish and seal. The sanding went well. After the whole table top was sanded I was excited to get the finish on and finally have a table that didn't look beat up and that I was embarrassed of. I bought some Minwax Polyshades from the store because it sounded like it would save some time (applying both stain and seal together). I was also concerned about the weather outside. It is getting cold so I didn't want to apply the finish to my table indoors because opening up the windows to ventilate would chill the whole house. I used the garage as my workspace. I was told that the temperature shouldn't matter, and the directions and labels on the can didn't warn of any temperature issues that I found.

I applied the first coat. Then let it dry almost a full day. Then I sanded it down (as the directions said) with steel wool (0000) and wiped away the dust. I then applied the second and what I thought would be the final coat. The second coat made the wood much darker than the first. It made it dark to the point that I don't dare apply a 3rd coat because I'm worried that the finish will be so dark that it will hide the wood grain altogether.

That brings me to my biggest concern. When the second coat had dried after a full day in the half shut garage I noticed that when I ran my hand on the table that it had small lumps/bumps all over it. I used a natural bristle brush to apply the product because I was warned that foam brushes might produce air bubbles.  I'm not exactly sure it the lumps are dried air bubbles or if they are bits of dust from the garage itself. Perhaps it's mix of both.

Can I just sand them out with 220 or the steel wool? Or will that ruin the finish and force be to start again.  I don't know if the tabletop can take another sanding. Seems like the wood that displays the grain is getting rather thin.

Please help/advise.

Thanks

ANSWER: Hey Glenn, to remove an old finish, it must be chemically stripped...SO many people think it's a good idea to sand when trying to remove a finish, and I'm not sure where they get this idea. The ONLY time one should sand off an old finish is on a floor, and only a floor that is solid wood.....Sanding does NOT remove the old finish at the pore level, unless done very aggressively, and that can easily ruin a piece of furniture. Also, your decision to put Poly over what was most likely lacquer,(although it could have been one of a number of different finishes...) was not the best either. Poly and lacquer are not really compatible, and because the lacquer was already lifting, and failing, an attempt to put anything over it wasn't going to last long...I would've been a little more insistent at the point the finish started to fail, if it really was that soon after buying it....that's clearly a manufacturers defect, and it should have been covered. If your finish is now rough to the touch, you can sand it, but 220 is way too rough for that...you'll want 400-600 grit to do that, and you only want to sand it until smooth to the touch. Then I would apply a clear coat...not the polyshades,..that won't darken it anymore yet will give it a final coat of protection. Right before you apply the final coat of clear, use a tack cloth and wipe down the top. Also make sure the garage door is closed and no one is in there for an hour before you do the final coat so the air has a chance to settle. I'm still concerned that you didn't properly remove the old finish, though, as your final product will be totally relying on the lowest level of finish for adhesion...and that would be the initial finish that was failing....the smoothest finish would be achieved by spraying, if you have the knack, and the Minwax Poly in the aerosol is capable of a very nice finish if you have the experience to do so....it does take a bit of skill to spray on a finish, but these spraycans are quite capable of applying a very smooth, professional looking finish...the other product I love, and highly recommend, is a Gel Urethane wipe on products from General. This is one of the best and most foolproof finishes of all, very light in color, (almost like a lacquer) and extremely easy to get Pro results with.You just apply it with a "pad" of cloth,apply it to the whole surface, and finish by wiping with the grain, evenly...It's available at WoodCraft or other places online.... Hope that helps a little, post back if need be- regards- Greg

http://www.woodcraft.com/Product/2005555/16556/Satin-Topcoat-Gel-Stain-Pint.aspx

---------- FOLLOW-UP ----------

QUESTION: Thanks Greg I appreciate your timely and great insights and advice.

I have just a few follow up questions. Would a disc sander with 400-600 grit be alright for sanding? Or would it be best by sand the surface by hand?

Secondly, I have a young family that could be hard on the table. Be it through utensils, toys, you name it. Would the Gel Urethane or the spray on poly still be your recommendation of choice? Or would something like an epoxy bar coat be better for durability without hurting the aesthetics too much? And are both equal in skill to apply or is one far more newb friendly?

again....thanks!

Answer
Power sanding any finish is to be avoided at all costs....only a light hand sanding should be necessary. If you have that rough a surface, then the prep was not done properly. You should only be finishing a smooth, properly prepped surface, and that shouldn't require any such sanding....either of the urethanes should yield a hard enough surface to be washable and pretty durable...but you could apply a catalyzed urethane or conversion varnish....but these finishes are not really for the novice.They take knowledge, experience, and some skill to apply. Epoxies are not recommended for a table, and they have to be poured which takes some experience, and they're really not reversible. Plus they look pretty 'industrial'....the General Gel is a great finish...and it can be reapplied simply by cleaning well, maybe lightly scuff sanding with some 400 and applying another coat, (most urethanes can be recoated in this way). My new fave though, is the Zar Ultramax, which is an oxygen coalescing, dual drying technology, oil modified Urethane, which is tough enough for floors...I apply it with a pad painter, and it levels out, and dries beautifully for a waterborne finish.Any or all of these take a bit of skill to apply, though, and experience is hard to get unless you actually work at it....you're entering the realm of pretty advanced finishing....but the good news is you can always strip it and start over!!

http://www.amazon.com/United-Gilsonite-Lab-36112-Polyurethane/dp/B001CESLUE/ref=