Water-based polyurethane - Spider cracks on edges?

[Chris Rich]

The reason I said that is when I called them on the phone, they told me definitely not to use floetrol. I am in las vegas. It's about 45% humidity today only because we had rain last night but normally, it's down in the teens. I'll give the thinning a try at 10% using the extender along with the other suggestions. It's clear that some of my techniques were not exactly the norm so I'll try and do things a bit more consistent on my next pass.

[scott vroom]

"Hmm..so far, the response I got was less than helpful...

Not sure. Try adding about 5% Flotrol which you can get at Home Depot. It could be that in the dry climate the product is flashing off too fast. The Flotrol will help slow it down a bit"

"The reason I said that is when I called them on the phone, they told me definitely not to use floetrol. I am in las vegas. It's about 45% humidity today only because we had rain last night but normally, it's down in the teens. I'll give the thinning a try at 10% using the extender along with the other suggestions. It's clear that some of my techniques were not exactly the norm so I'll try and do things a bit more consistent on my next pass."



I'm confused. Are you saying that someone at GF emailed you with the floetrol suggestion? And then when you called GF on the phone the chemist said to use extender instead? I've never used either with GF, but yes I was reminded that they have their own brand extender.


If low humidity turns out to be the culprit then I suppose you could invest in an inexpensive humidifier for your shop when finishing.

[Chris Rich]

Yes, that is what happened. I think they would prefer us to use their extender and they said, chemically, it's different than floetrol. The whole thing is quite odd but the best I can do is try to follow all the suggestions and tighten up my procedures.

[scott vroom]

Chris, I checked the GF website and found this article embedded in their blog:

https://generalfinishes.com/blog/2013/07/enduro-extender-featured-family-handyman-magazine-julyaugust-2013-edition#.VOy0pbDF-cI

I think what's going on is that GF has developed in house an extender that, while somewhat different chemically, may have the same or similar performance as Floetrol with Enduro Poly. If it were me, to be on the safe side I'd go with their GF Extender if for no other reason than to avoid warranty issues down the road.

10% humidity is really, really low and I think it's reasonable to try the extender to see if it solves your cracking problem. Let us know how it turns out so that we can learn along with you.

[Chris Rich]

Thanks for the info... I'm just waiting for some 320 pre-cut sandpaper to get delivered and then I'll try this weekend and report the results. Again, I appreciate the help from everyone in this forum

[John TenEyck]

I noted that the GF article also said that "Floetrol is another great additive", which makes the comment by the one GF person not to use it confusing.

John

[scott vroom]

John, I'm thinking that GF is trying to make a market for it's own extender, and are pitching it as "chemically different" than Floetrol despite some evidence that the net effect of both additives is the same or similar. I don't blame them for that, but they should at least get their story straight between themselves

[David Kuzdrall]

Uncured poly (and many) cured types are not resistant to DNA. This could be a contributing factor. Please note that there is a big difference between drying and curing.

[Chris Rich]

OK, so I've been experimenting. I emailed GF to ask them how many mils the finish should be because it wasn't in their tech document. They responded 2-3 mils. At 2-3 mils thinned 10%, I get spider veins. The finish is drying too quickly in my environment (72F @ 30%RH). I then noticed that the can actually says 3-5 mils so I tried at 5 mils and that seems to work much better. In terms of my spraying technique, I think I'm not quite doing it correctly. I haven't been doing a cross-hatch pattern and I think I should. I'm going to turn down the flow a bit and do a cross hatch.

[John TenEyck]

That's interesting. My shop conditions are not far from yours at about 65F and 30-35% RH. The time I had spider veins with Clear Poly I probably had a pretty thin coat, too. I'm not so sure that spraying a cross hatch pattern is a good idea. It seems to me you want to spray a single, wet coat to get your 3 - 5 mils, so that the film can flow out. Spraying a cross hatch pattern means you are spraying two thinner coats, and the first coat is going to start drying before you get the second one on top. But I'm wrong a lot, so good luck and let us know how it works out.

John

[Chris Rich]

Thanks John,

I tried doing a crosshatch and it seems that the results were much better. I just turned down the volume a bit. The reason I wanted to try the crosshatch was that when I did a full pass at 5 mils, I notice that when it started to dry, I notice a faint white shadow line where some parts were curing faster than other but I do agree that it looks like it flows better. Probably my technique but something I noticed. For any one that's interested, my setup is as follows:

Wagner Conversion Gun
GF Enduro Pigmented Poly thinned with 10% GF extender
About 10psi at the trigger and 25 psi at the gun
#4 tip (I tried a number 3 and my gun couldn't do it)

You're results and setup may vary

Thanks again for everyone's help!

[David Kuzdrall]

How large is the piece you are spraying? Just curious with the size vs crosshatch technique.

[Chris Rich]

These are 21 cabinet doors so varying sizes but generally small...

[Chris Rich]

Actually, it turns out that the white "ghost lines" seem to wipe off with water and a soft cloth. Some kind of reaction during drying I guess. So, I'll go back to single pass which does seem to flow better...

[John Sanford]

One thing to keep in mind is that your wood is also at a very low moisture content. Between it sucking some moisture out of the finish and the flash off the outer surface, you're simply losing too much moisture too quickly. As an experiment, try wiping down a scrap piece with a damp cloth (lint free of course) just before shooting it. If that does the trick, then you could experiment with shooting distilled water (no mineral spots) for moisture (quicker), then shooting the poly. It could be worse though. You could be finishing outside during June. (I did a fair amount of brushing lacquer when I was living in Vegas....)