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Discussion Starter · #1 ·
I have been trying to finish a fir front door with a WB Acrylic-Urethane clear coat (gloss on exterior, satin on interior). The door was stained with a tweaked old masters brown mahogany wiping stain. I put about 4-5 coats of gloss on the exterior door. The interior received 2 coats gloss followed by what should have been 2 coats satin. That is where the trouble seemed to start.

The coats kept drying with small rough specs in them. I first thought it was dust contamination. I filtered the finish (applied by HVLP), blew the door off to remove dust, vacuumed the door, then tacked the door (with a rag damp with water), then sprayed the door. Specs would still be in the finish. I tried again, same procedure again, same problems. I thought maybe I was not removing the contaminants with enough sanding, so I sanded with 150 on a random orbit and followed up with 220, 320, 400, and 600 by hand with the grain. Then I did the filtered finish, blow, vac, tack thing again. SAME PROBLEM (I had switched to a different batch at this point as well).

I finally did the sanding and cleaning procedure and finished it with StaysClear instead and brushed it out so I could draw more finish out of the detail areas (it was beginning to get a little cloudy) and got rid of the specs. Dropped the door off to be installed, and now the builder and HO do not like the faint brushmarks in the the door and now I have to redo it again, with a sprayed finish.

In the mean time, I have become pretty certain that the defoamer is the culprit and introducing small air bubbles into the finish that do not pop but stay inside the film or are so small I cannot see the crater when the dry. I talked to the company rep and was told that the defoamers in the WB finished can be very touching and why it happens to add a little paint thinner to the product and that will fix it. Now, I just got done respraying the door again using the original product (which I normally love by the way, it is the best leveling and hardest WB clear coat I have used) and the same problem happened again.

I am currently planning on one of two options:
1: Smash the door into very small pieces, burn it and scatter the ashes as far as possible. When builder and HO ask about the door, pretend I have no idea where it went:whistling2:

2: Thin down stayclear and shoot it again (not a huge fan of staysclear, never thinned it down enough for HVLP before).

Anyone run into anything like this before, it is a first for me?
 

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Smash the door into very small pieces, burn it and scatter the ashes as far as possible
I would pay good money to see this option

....never dealt with this issue, sorry I can't be of help...I'll just be a cheerleader while your getting out the lighter fluid
 

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Rock On
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It's that crappy water poly
Blech
 

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Discussion Starter · #6 ·
The first finish I used was Graham's Ceramathane, a urethane acrylic. I have used the gloss on an exterior mahogany grill surround and it held up very well with no protection from rain, snow, sun, etc. It actually gets quite hard, feels almost like precat lacquer.
 

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Only thing I saw wrong was the lack of sanding sealer... the grain in the wood will always cause problems unless actually sealed before poly.
 

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Discussion Starter · #8 ·
I have found that 2 coats prior to sanding seems to seal the grain. I have thought about using a shellac sealer before but do not think it would be the best choice for an exterior door and I thought most sanding sealers where really interior only (I would think they would tend to be too brittle for the exterior side at least).
 

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Discussion Starter · #11 ·
I do think after messing around, it was bubbles. I stripped the interior side of the door down completely, sanded out the stain, re-stained the door, and finished the inside with lacquer. The outside has a little bit of the same things also, but not as bad. The funny thing is I have done three kitchens (painted and glazed) using this as a topcoat with no problems at all.
 

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Epoxy Dude
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Hi Dean,

I think I can help you.

First, while WB Acrylic Urethane IPN (Interpenetrating Network) coatings can have foam issues, I have a feeling that you might be seeing something else. I believe that you might be seeing hollow glass spheres rising to the surface of the coating. There is a fine line between spraying these coatings too thin or too thick.

First, you mentioned that this is a clear. You can't really modify a clear with ceramic microspheres because they are either gray or white. So, you would see them in the clear. SO, some manufacturers cheat a bit by using glass bubbles/spheres instead. The glass spheres make the coating seem very hard. Since they are round, your fingernails slip over the film instead of cutting into it.

Here is the problem. The glass shperes they use are hollow because solid glass spheres are extremely heavy (they sink). So, solid spheres would get burried in the coating film unless you apply the coating precisely 1/2-2/3 the thickness of the diameter of the solid spheres. Basically, spraying this precisely is difficult... even for a computerized machine like a Spraymation.

So, they use hollow spheres. Since they are hollow they have a very low density (they float).



Since the spheres float they rise to the surface of the coating and stick out a bit to give you some advantageous properties. If the coating has too many spheres they can compete with each other to reach the surface. When they compete, they end up pushing some beads out of the film.



What you are hoping for is for the glass spheres to barely reach out of the surface.

So, you might need to experiment with film build. You're striving for a delicate balance. You want to spray on enough material for coverage without flooding it. If you spray it too thick... the spheres will rise to the surface and compete for surface area at the film surface. So, the more liquid you spray the more glass spheres you will have in the liquid. BUT, you still have the exact same surface area at the top of the film. ideally, you would have a solid matrix of glass spheres without any spheres beneath another sphere trying to push it too far out of the film.

Last, as I mentioned... yes... defoaming can be an issue. If it actually ends up being one here I would suggest trying some Drewplus W-4300. You can get more information on it here:

http://www.wolverinecoatings.com/Pictures/DrewplusW-4300.pdf

You can call and get a sample send to you. DON'T go overboard with this... it is probably the most effective defoamer with the fastest bubble break that I have EVER seen (I've evaluated hundreds maybe thousands of them)...

Ok... one more option...
On the last coat, use and IPN Acrylic Urethane clear WITHOUT 'ceramic'...

Good luck on your project...
Wolvie
 

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to my knowledge you should definitely use a sanding sealer also I don't think you can put latex varnish on an oil wiping stain. I always uses old masters wiping stain with an oil sikkens door/marine varnish
You bring up some good points.

You can use waterborn poly over oil stain. The stain needs to be dry.

There have been times though, that any finish would bubble on some types of porous wood and had to be sealed.

I think the op is using wb for his own purpose. Maybe quick dry time, maybe clarity or hardness. It dries super clear, as opposed to quick dry poly, which will orange or yellow over time.
 

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Discussion Starter · #15 ·
I did one final coat on the exterior with gloss, this time, FISH-EYES. I went to the paint store this morning and check 3 different batches, all fisheyes. Absolutely unbelievable. If I had not won a 52" 1080p hi-def DLP TV from this company last year, I try this product again. In the past the track record with this product has been great, now I do not know if I will give it another try or not.
 
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