Finish Problem

[Gary Lange]

I have a friend of mine that sent me this message and I don't have an answer for him anybody have any ideas.

I have a little prob. I have a Mahogany door that i had bought from a yard sale. It is new raw wood. I put 1 coat of polyurethane(Olympic brand) let it dry for 12 hours and applied a second coat. The second coat only dried in spots. I let it set for 12 days and still spots on the door was wet. So i sanded it all back down to the wood and put the first coat on it( switched to Helmsmen to see if the Olympic was contaminated) let dry for 3 days then used oooo steel wool then applied a second coat. It has been setting for nine days and still doing what the other brand was doing and i can't figure it out. The first coat is beautiful lays down slick as a babies but but the second one acts like it is not bonding. I don't know what to do. Has anyone else had this prob?

[Phil Phelps]

Madening, huh? Have you put it in the sun for an hour or two? I've had incredible luck using the sun. I've also ruined a few things so keep an eye on it. Sounds like something leeching out during your clear coat process. You may have to sand it back down and seal it. You'd think the urethane would have been a good sealer, but something chemically is hapening here. Do have a real pro in a paint store to run this by? He might have a sealer that will work. Let us know what you end up doing, right or wrong. Hopefully, right. Good luck.

[Mark Roderick]

Going to a local paint store is a good option. Another is to visit Target Coatings on the web, and give them a call. They sell only water-based products and are sure to sell exactly what you need.

[Tony Bilello]

How old are these products and what weather have they been subjected to?
Have they been through high heat in an attic or below freezing temps?

[Gary Lange]

Brand New can bought and used that day.

[Tony Bilello]

Sorry Gary. I cant be of any help to you. It's time for you to call up the coating manufacturer and ask for a tech rep. He should be able to help you.

[Gary Lange]

Her is what he last post said!

Thanks to everyone for you help! Ricky, i have tried it in the sun and the finish spiderwebbed and i use 150 grit sandpaper after the steel wool and always use a tackcloth. I was tryin to eliminate what the problem was by switching polyurethane, using tackcloth noy using tackcloth, different stir stick, different brush,etc,etc. I think that i am gonna try the sealer deal next. I am gonna sand the door back down and give it a try. I asked a friend of mine that finishes hardwood floors and he said that he has been doin this for 25 years and has never heard of this before. I told him that if it can be screwed up i am the man for the job! This is aggravating as all get out. Thanks again guys.

[Howard Acheson]

What did you do to prepare the door for finishing? You did say that it had not been finished before, didn't you? How long and where had it been stored? Is this an inside door?

One thing that keep coming into my head is that you are running into complications from some type of contamination. My first step would have been to remove the first coat of finish using a chemical paint stripper. Sanding does a poor job of getting stuff out of deep pores like those in mahogany. I would also have sprayed on a couple of coats of a dewaxed shellac to act as a barrier coat to any residual contamination not removed by the paint stripper.

Finally, throw away any store bought tack cloths. They are a big source of contamination and if there is any contamination present, they are guaranteed to spread it around. Vacuum off any sanding dust and then dampen a shop towel with mineral spirits and use that to wipe off any last minute dust.

[Barry Rowland]

Vacuum off any sanding dust and then dampen a shop towel with mineral spirits and use that to wipe off any last minute dust.

Or, use a micro fiber cloth either dry or with a light mist of water to remove sanding dust, or other particles. That way you won't have to deal with the mineral spirit vapors.

They do make tack cloths for automotive finishes that are great for woodworking too, as they contain no wax or silicon. But they cost
way more than a 6 pack of micro fiber cloths at walmart that you can wash and use over and over again.

[Howard Acheson]

Barry, I am not an advocate of micro fiber as a tack cloth. Sure it will pick up dust but, like a tack cloth, it will pick up and spread contamination for the rest of it's life.

As I said in my first posting, the safest "tack" cloth is just to dampen a paper towel with mineral spirits and wipe it gently over the surface just before applying the finish. It will pick up any dust just as well as a tack cloth. As it is disposable after each use, you don't risk picking up contaminates and spreading them to other finish surfaces.

[Barry Rowland]

Howie, I have found that if you wash the micro fiber cloths in warm water and mild soap, this causes the tiny fibers in the cloth to release the contaminates and any dust particulates. Then we have a contaminate free cloth to use again. I have yet to have any issues with
finish quality, besides my personal screw ups. But let's not go there!

Is there something I am missing here about micro fiber behavior? Do you have some techy info on micro fiber that says something different?

If so, I'd love to read it. I'm always looking for a better way to do things.

[Howard Acheson]

Barry, if the microfiber cloth picks up any liquid, oil or silicone contamination, washing in a mild soap is not going to clean it. Plus, in most cases you will not know when it becomes contaminated so unless you decontaminate it after every use, you still run the risk of spreading contamination.

There have also been some reports of the microfiber picking up wood shards which become embedded in the cloth. Try dragging a microfiber cloth over a sanded wood surface. You will frequently feel the drag as shards (small microscopic splinters) are snagged. These shards generally are not removed by washing. These shards can cause damage to a new, very soft finish.

Folks are certainly welcome to use whatever they want for picking up dust before applying the final coat (the only time when absolute cleanliness is paramount). But, IMO, there is nothing better than a shop towel dampened with mineral spirits or dampened with water for waterborne finishes. If you feel that microfiber cloths are working for you, continue to use them.