Bounceback w/HVLP??

[Art Greenberg]

Agreed, an easy experiment.

Thanks.

I've gotten plenty of input on this, and I'm anxious to experiment now. All I need is the time ....

[Art Greenberg]

Uh ... yes!

Robert, thanks so much for all of your suggestions. I hope to get back to this this weekend. I'll let you know how I make out.

[nailshooter41]

Good luck! I hope it works out and you post some results. I will be out of pocket this weekend, but will certainly check back when I am available.

Robert

[nailshooter41]

This may be a double post as I was called away and was unsure if I pushed "send or not".

As with everything I scribble electronically on this group, this is my opinion/observation. So we are sure we are both on the same page, please remember in context that the OP stated that he was painting, not clear coating.

I think the actual problem may be as noted, the equipment. I intentionally bought the Fuj as it has the highest air delivery of any unit I could find. Their gun was not my favorite, but hey... you can't have everything. And since I have learned to use it, the gun works great.

I would guess that the CHPOS probably is a two stage (or maybe a one!) that doesn't move enough air to deliver the thicker materials. But since you are or have been getting good finishes with your clear coats, it means that you know what your gun can do and are thinning properly.

However, if it is shooting clearcoat properly and not an heavy solids coating, that could mean two different things.

As far as shooting the shellac the first could be that with your lower powered machine (has Festool come out with an HVLP yet?) it may not be able to pressurize the cup and have enough air left over to atomize (we all know that is the incorrect term, but to stay on subject, we all understand the concept) the coating or paint and push it to the target.

Solution: Whether it is clear or Stain Block for painting(white) Bullseye, thin it with the proper thinner. With the thinner solution, give it more air flow and spray.

This high humidity and fast rising temps kill alcohol based finishes. For me, no matter what I do in this weather any finishes except paint are dicey. I can usually get some nice blush on lacquer with no problems at all with 87% humidity.

Spraying outside in the elements or in an unfinished (unairconditioned) house or in a garage is so different from spraying in nice shop. Now with the temps and humidity so high, I am glad I am doing mostly repairs and no finishing.

BUT... as they say, the show must go on. If I were in your shoes, I would drag out that shellac and really give it a dose of thinner. Here's my thinking - you know you can build the finish on these since the shellac will simply dissolve into itself. So I would take it from another direction to test it out. Think about it for a second; you know you are on the right track when thinner is better. Since you are essentially shooting resin with a solvent, who cares how much you thin?

I would cut the shellac by about 50% due to heat and humidity and then try it at 60 - 40 alcohol to shellac. The shellac will stick... it just depends on what you are trying to do with it. If it is a sanding sealer coat on a nice wood, you don't need it thick. Since the shellac will dry quickly, you can see what it will do on a test piece. I would thin the hell out of it then spray about a 3 mil coat on it and see how it does. That just may do the trick. If you like the results, it is certainly easy enough to build the coats. To me, it's worth a pint of material to try it out.

In a push job in similar weather, I was having so much trouble getting the shellac out of the gun I was ready to put it on with a heavy nap roller and be done with it. The dried coating texture would have been the same.

In a moment of really pissed off inspiration I thinned the Bullseye to a 70/30 alcohol to shellac (I also had the wrong aircap for the gun and couldn't get it to behave with the one I had with me) and it worked fine. I sprayed a pattern that was fairly thick, but since it was mostly solvent it dried thin (1/2 mil maybe?) and then in about thirty minutes (just able to leave a fingerprint in the finish) sprayed another coat spraying the opposite pattern. It worked great.

You can get away with thinning the daylights out of any resin finish (OK, to a point) since there are no solids to fall out of solution. You can thin them so much that they don't perform properly, but I wouldn't worry about that with shellac.

I dont' know if some of the stuff we get has green veneer or outgassing fish guts glue made with diesel, or what. But I never had that problem until a few years ago. I went for a few years thinking I wasn't doing the prep right, but now I think it is something to do with the wood.

Something is different, and if that is the roughness you are getting when you spray, I am getting the same.

So another voice is heard...

Will you be getting a new 4WD Japanese carrying case for it?

I am tighter than a top on a banjo, and I don't like buying new tools anymore. Just as an unsolicited opinion, I would probably goof with that setup a little more. If it worked for you in the past, it should work fine now. No, it won't have the power to spray some of the finishes as easily, but unless you are using finishes specially designed for HVLP you will be mixing up new formulas anyway with a new unit. As with any of this stuff, there is a lot to be said about being comfortable with a certain piece of equipment.

On the other hand, it sounds like you have sure gotten you money's worth out of it and more. It may be time... some of these new units are just nothing short of great.

Robert

[Swingman]

Considering the market, truck dealers should take a page from the 50's bank/gas stations promotions and offer your choice of Festool, Fuji, et al with each purchase.

Thanks for the comments, Robert.

My best luck so far shooting shellac with this CH rig is roughly 50/50 60/40 shellac - alcohol thinning, but with the table I need to do this morning, which is not of much import so will stand a little experimentation, I might kick up the alcohol in the ratio and see what happens.

To muddy if up even further, I've also had a big differences in the final results when using 99% Isopropyl versus denatured when the weather/high humidity is involved (I only shoot outside, and have to wait on the weather ... and the ubiquitous yardmen with a weedeater/leaf blower).

I usually thin with 99% isopropyl when the humidity is this high, and actually shoot it a bit closer to the surface. I don't analyze why, but it seems to work.

Like sanding, I dislike finishing, but the importance is all too obvious, so the piper must be paid in both effort and understanding.

Your (and Mike Marlowe's) analyzing helps ... thanks again!