Porter Cable HVLP????

I am pulling my hair out here. I have been using a Porter Cable HVLP conversion gun for about a year now. I spray a lot of water base poly, and laquer with it.

Anyway my major problem is with an orange peel finish. I usually disregard it because I use a satin finish, and it doesn't show too bad. But on my current front door project , I'm using a Target waterbase gloss eurethane. I'm sick of resanding out the orange peel and trying different settings.

Problem is this gun has 5 different variables, and unfortunately I don't have the super secret decoder ring. There is psi, air volume, material volume, tip size, fan size, and thinning. AGGGHH!!!! So I've got a one in a million shot of getting the right combo to having a perfect flawless finish. I increase the air pressure and I get a finer spray, but then it dries too fast and the overspray fouls my nice finish. Decreas the pressure and the orange peel gets worse. Increase material flow, and it globs and splatters, decrease and it is spotty, change the fan size and I get runs....:mad:

So, does anyone with experience with this gun have the "MAGIC" setting to eliminate orange peel??? Any advice would be greatly appreciated.... I'm thinking maybe thinning it a little more, but I don't want to waste much more finish on "experimenting".
Thanks.....

You can try adding some lacquer retarder.

I've got three of those guns.

Thin your mixture.

thinning is the answer. whatever you spray needs to be able to "flow out" before it tacks. i have no experience with the waterbased products but finishes that orange peel are usually tacking up to fast. so depending on the product you`re spraying either thinner or retarder should fix the problem......02 tod

Thanks for the advice, guys. I thinned about 20%, and ran the gun pressure at 30psi. I laid on a heavier coat with the door horizontal. That gave me an even coat, although a little heavy. If it was virtical, it'd probably run, but at least it's done now with a lot better results....

I was hesitant to thin it very much, because the product says ready to spray and makes no mention of thinning.....

Thanks.....

Quote:

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Originally Posted by Scott Parks

I was hesitant to thin it very much, because the product says ready to spray and makes no mention of thinning.....

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I read somewhere, probably in Jeff Jewitt's book, that the reason that products say not to thin them is that doing so affects the Volatile Organic Compound (VOC) emissions. Making the product thicker reduces VOC emissions. To make the VOC information on their label true, they tell you not to thin.

Quote:

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Originally Posted by tod evans

thinning is the answer. whatever you spray needs to be able to "flow out" before it tacks. i have no experience with the waterbased products but finishes that orange peel are usually tacking up to fast. so depending on the product you`re spraying either thinner or retarder should fix the problem......02 tod

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I agree. I bought a Walcom GEO from Jeff Jewitt that he used as a prop in his "Complete and Illustrated Guide to Finishing" book. His instructions to me were to dilute the lacquer 1:1 and add a capful of lacquer retarder for each quart of lacquer sprayed. I have followed this advice and it works great. If you have a larger size tip, you can use a 2 part lacquer to 1 part thinner ratio.

Try that recipe and you will be happy I think.

Quote:

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Originally Posted by Scott Parks

...Problem is this gun has 5 different variables, and unfortunately I don't have the super secret decoder ring. There is psi, air volume, material volume, tip size, fan size, and thinning. AGGGHH!!!! So I've got a one in a million shot of getting the right combo to having a perfect flawless finish. I increase the air pressure and I get a finer spray, but then it dries too fast and the overspray fouls my nice finish. Decreas the pressure and the orange peel gets worse. Increase material flow, and it globs and splatters, decrease and it is spotty, change the fan size and I get runs....:mad:

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Hi Scott

I eliminated one variable-opened my air volume control (bottom of the handle)all the way and let it rust in that position;) Use the pressure regulator to control air flow. I'll be interested in the replies You get, I had something very similar happen with WB Poly.

Curt

Quick update....

I've sprayed 4 coats thinned at about 20%. It goes on heavy to get total coverage, but as it dries it shrinks leaving an ever so light "dust" in the spray. At this point each coat is identical and does not get 'perfect' gloss....
Thanks for the replies....

Scott,

I haven't sprayed waterbased products for a while, however the principles are the same as solvent based finishes.

What are you thinning it with? Water? Does Target sell a reducer? If you using water at 20% your likely changing the finishes ability to level out before tacking. Waterbased finishes are more dependant on proper temp. and humidity than solvent based. If it under 70 degrees in your shop, try thinning 5% , heating your finish (sit the gallon on a heating pad), and bumping up you PSI (35-40 psi with the trigger pulled air only/half way). This should give you a good flow and the ability to put down a heavy enough coat.

Also, as I understand the best waterbased gloss finishes are a result of buffing rather than "off the gun". However, you need to wait to buff until the finish is cured ( 1 week?) or force cured with IR heat lights.

Good luck.

You have a conversion gun. You need a regulator at the base of your gun at the hose connection. Crank up your regulator from the compressor to 80 psi. Thin your material 40 to 50%. Open your "new" gun regulator to it's max and adjust form there. 30psi from the compressor is too low, unless you are air brushing. Plus, your material was way too thick. Also, strain your mixed material through a nylon stocking. Practice with lacquer, reduced 50%, it's not that expensive.

Also, a very important bit of advise. You need to really "clean" you gun. Conversion HVLP's are notorious for difficulty in cleaning. There are more areas that clog than with a siphon gun. You need to tear it down, completely. Soak the parts in lacquer thinner or MEK. Buy an aerosol can of carburator cleaner and spray liberal amounts on the nozzel and tip. Use the scrub brush that came with the gun. Replace the plastic tube and check valve. Water base products are much harder to clean than solvents.