Need help with oil based poly.

[mike mcilroy]

I am trying to finish a 13' long bar top which has a two part poured epoxy top. I tried sanding then using a wipe on poly but it came out terribly streaky. I'm going to have to sand it then I will try a brush on finish. I am wondering if it would be better to brush in shorter sections, sanding any over laps before the next coat. Any help would be appreciated

[Todd Burch]

I think you would be better off brushing it on heavy and fast, keeping a wet edge. The faster, the better.

[Howard Acheson]

Just curious why you are overcoating the epoxy with a poly varnish? Poly varnish does not adhere well to epoxy even if the epoxy has been aggressively scuff sanded.

[mike mcilroy]

Trying to get a more scratch resistant top and I can't get the Behlens Rock hard table top. Thought this would be next on the list for scratch resistance. Didn't know I would have the adhesion problems. What should I substitute? Dewaxed shellac then the poly?

[phil harold]

There is a product called Rock Miracle, it containes a chemical called Methylene Chloride and will remove the epoxyeasily, then use your poly

been there done that

[Phil Phelps]

There is a product called Rock Miracle, it containes a chemical called Methylene Chloride and will remove the epoxyeasily, then use your poly

been there done that
Sounds messy and dangerous.

[mike mcilroy]

I don't want to remove the epoxy just top coat it.

[Jim Becker]

A non-poly varnish is preferred for this kind of application...and the adhesion is a good part of the reason. Poly doesn't like to stick to itself, quite frankly. You can try a coat of dewaxed shellac between the epoxy and the poly if you must use that form of varnish. But it's not going to perform "substantially" better than a good, high quality alkyd or phenolic resin varnish. The polyurethane varnish I put on our kitchen table is the worst performing finish I've ever used...and it's soon going to be stripped and replaced.

[Howard Acheson]

Trying to get a more scratch resistant top and I can't get the Behlens Rock hard table top. Thought this would be next on the list for scratch resistance. Didn't know I would have the adhesion problems. What should I substitute? Dewaxed shellac then the poly?

In my experience, a fully cured epoxy is harder and more scratch resistant than either Behlen's Rockhard or Waterlox Original. Specialty oil based or waterborne floor finishes are very hard and scratch resistant also. But, I don't know that they are MORE scratch resistant than fully cured epoxy. BTW, epoxy continues to cure for it's whole life. It is significantly harder after 3-4 weeks than it is after initial cure.

Be careful if you attempt to use any type of paint remover. Many of them will soften and damage epoxy.

[mike mcilroy]

Right now there is only one coat of Minwax Fast Drying Polyurethane on. It would be easier just to sand down to the epoxy. The epoxy had cured 3 weeks before I started this topcoat it was my understanding from many different sources that it was common to topcoat the epoxy because it wasn't as scratch resistant as other finishes it just gives the thicker build up quicker. This is the first bar I've made and the first time with epoxy. I'm just getting more confused.

[Todd Burch]

I coat epoxy sanded to 220 all the time with pigmented Lacquer - no adhesion problems ever.

[mike mcilroy]

Are there any signs of this adhesion problem that would show quickly in a week or so? I'm supposed to go back and put more coats on next weekend.

[Todd Burch]

A good test to perform to check adhesion is this.

Finish a piece of scrap just like the real piece is being finished (or will be finished). In about 1 square inch, with a sharp razor, cut a grid, say, of 1/8" apart lines. Checkerboard style. Put a piece of tape over the cut grid and then pull off. See if, what and how much comes off with the tape.

[Howard Acheson]

Mike, oil based finishes must be fully cured before they develop full adhesive qualities. For most oil based finishes, this can take 3 to 4 weeks. Any test for adhesion should wait for at least a month.

The test Todd describes is a standard ANSI test for adhesion. However, there is a specific tape that is specified to be used. I've used standard Scotch tape but that can lead to variable results.

[mike mcilroy]

Thanks guys. I guess I'll just put the other coats on this weekend and hope for the best.

[mike mcilroy]

Still working on the same bar top. I am using Min wax Fast Drying Polyurethane. I keep having problems with bubbles. I waited three weeks before top coating the epoxy. Wipe on poly does not bubble but the brush on version keeps bubbling. I have tried thinning with paint thinner (about 10% paint thinner) and it still bubbles. The epoxy layer was about 1/8" thick could it still be gassing out? Or should I try another product or thin this product even more? Any suggestions would be appreciated.

[Prashun Patel]

To ask a different question: What sheen are you using for the poly? If it's not pure gloss, then the streaks could be coming from the poly being improperly mixed. I humbly suggest you use a gloss product if you want to wipe. Many say it's easy to wipe satin, but I'm not one of them; then again, I'm a relative newbie to finishing...

The trick to wiping on oil poly or varnish is to wipe it on quick and not work the surface too much.

[phil harold]

Still working on the same bar top. I am using Min wax Fast Drying Polyurethane. I keep having problems with bubbles. I waited three weeks before top coating the epoxy. Wipe on poly does not bubble but the brush on version keeps bubbling. I have tried thinning with paint thinner (about 10% paint thinner) and it still bubbles. The epoxy layer was about 1/8" thick could it still be gassing out? Or should I try another product or thin this product even more? Any suggestions would be appreciated.


Minwax Fast Drying Polyurethane is not my favorite, dries to fast to let things flow and smooth out in my opinion

I once i was having problms with bubbles in polyurethane forming and was told to heat the surface with a torch to remove the bubble/s
as dangerous as this sounds it did work
had something to do with the heat and surface tension

I would test this method before doing it on location

good luck!

[mike mcilroy]

Both the wipe on and brush on have been gloss. I made an even thinner version tonight and there were just as many bubbles. I tried tipping off but it just seemed to move the bubbles or create more. I've tried foam and natural bristle brushes it does not make a difference.

[Loren Hedahl]

You might consider checking with an auto body supply and paint company.

The auto body guys use epoxy based primers regularly as a moisture barrier to prevent rust on steel. Then they use a color top coat of two-part polyurethane enamel and a final clear coat.

They get good adhesion and completely perfect dispersion of their metallic additives per the demands of the industry. Our local book store has scores of books on the subject.

[mike mcilroy]

Loren
The only thing about finishing epoxy at our local bookstore or library is Flexner and it is basically one paragraph which says for scratch resistance light sand then polyurethane. The bubbles I'm having problems with do not seem to be adhesion related. I am going to try a different brand name polyurethane if that does not work I will have to start researching your suggestion. Thanks for the options.
Mike

[mike mcilroy]

Tried a new brand of varnish. Same results think I'll try an axe and matches for my next attempt.