Latex w/ air gun, paint pot: report...

Awl --
Well, not bad for a home-moaner..... :)
My buddy picked up the HF pressurized paint pot http://www.harborfreight.com/2-1-2-half-gallon-pressure-paint-tank-66839.html
A hose from this pot replaces the siphon cup on the gun. So now I have quite the contraption, and it works!! I now have T1-11 gates (about 100 sq ft worth) painted in Glidden's Dark French Chocolate (exterior semi-gloss) -- which is like black with purple mixed in. LOL
Here's what was inneresting: I used old otherwise unusable HF black airhose (3/8" id) -- do not buy this stuff for regular compressor air, it springs more leaks than a sieve -- as the paint hose and thought all I would need would be a piddling 5-10 lbs of "pot pressure", but what a surprise when I blew out the hose at the end of the job, with straight compressor air, which had to "work" a little bit!! So it became clear that 40# is more realistic, for about 15 ft worth of hose. I could see this being much higher if working off, say, 24' ladder, but then you can hang this pot, so you don't wind up with unmanageable lengths of paint hose.
I didn't thin the paint, had about 30-40# of gun air while spraying. Yet, it kind of rapid-sputtered after a while, after being smooth-continuous. Still, it was rapid enough that it did not seem to affect the paint job -- which turned out great, and FAST.... the wife, who brush-painted the prime coat a few days before (and is STILL cryin over that job) was hilariously aggressive with this thing, seemed to be going for speed records. If there were no experimentation/marevelling at this new method, I think those gates would have taken about 2-3 minutes, for one person, vs. about an hour for two people.
But I am curious as to what that sputtering was about. Not enough paint pressure? Hmmm, it may have been much higher in the beginning, before I made it too low? Maybe I'll try thinning the paint as well, on the second coat.
The HF paint pot itself is OK.... you really have to torque down the clamp screws, I can see this being a problem later. But, the pot is heavy, sturdy, so if the top doesn't warp, I'll hopefully be OK. Nowhere near the quality of the old Sears unit I used in 1980, tho. The pressure regulator is so-so, certainly not precision, but it pressurized the paint. Seems to be a generic design for a bunch of labels. Grizzly has a wild one, with a stirrer and wheels! http://www.grizzly.com/products/2-1-2-gal-Paint-Tank-w-Gauges/H6329 .
The job went so quick I really didn't have much time to experiment! Very economical with paint, less than 1/2 gal on almost 100 sq ft of .T1-11, which has to be THE thirstiest surface on the planet, short of cloth!
What can one use as quick disconnects for the paint line? I doubt whether air quick disconnects would work.... for long! I'm thinking of just putting two 3/8 threaded unions at each end of the paint hose??
Pretty easy clean up, altho coordination is a bit of an issue, what with all the hose, parts, etc. Blew out the hose back into the paint can, cleaned the system with about a gallon of water, in place of paint.
Oh, the plumbing for this can be a bit of a handful, if you are not familiar with air and plumbing fittings. The paint hose fittings, on both the gun and the pot, seem to be some kind of hose/compression whatsit, which my hardware guy didn't recognize, but fortunately the thread seems to be a perfect match for 3/8 threads, so an assortment of reducing couplings (to1/4), hose barbs, quick disonnects for the air, etc, and the unit was running. A bit easier said than done, could have been pretty pricey if I didn't have most of that stuff laying around. I used brass so as not to screw up the threads too much, if the fit wasn't exact.
My buddy did some research into this, and whole-package units will spare anyone all the diy puttering. Still, a bit hard to find, it seems to me. But, my contraption-esque creation is less dependent on oem stuff, so I can mix/match as needed.
Anyway, appreciate all the previous advice, really helped the setup and the job. A lot of stuff is going to go a lot faster around here!
--
EA




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I spray stain and topcoats, not paint, but when I get sputtering I refilter what I'm spraying. My guess is there may have been small "chunks" that clogged the nozzle tip slightly. Thinning may help, but filtering is best. Your paint supplier should have the appropriate size screen and empty paint cans to pour into.
--
I used to like fishing because I thought it had some larger significance. Now I
like fishing because its the one thing I can think of that probably doesnt.
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I use a turbine HVLP system (Apollo) but sometimes the urethane sits in the pot overnight. Sputtering on this system is extremely rare, though.
I'm switching almost entirely to the 3M PPS Paint Preparation System <http://www.woodessence.com/3M-Paint-Preparation-System-C47.aspx , rather than using the pot that comes with the gun. Cleanup is a breeze, and it's really easy to switch between stains and topcoats for the small jobs (which is most of what I do).
The cups integrate a strainer, so the material is double strained. Once into the pot, and then again at delivery to the gun.
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I really like the turbine. The unit is very portable, which makes it easy-peasy to take onsite.

Haven't had any real problems as long as I make sure the nozzle is clean when I stop for the night.

I'm considering a second gun, but the one I want is spendy ($300+) so it will have to wait for a good justification (like being busy enough that it makes sense).
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A few comments which I didn't see mentioned previously.. you want to be absolutely certain that the paint pot pressure doesn't exceed a safe level. There should be a pressure pop-off safety valve incorporated into the design of the pot to ensure that the maximum safe pressure can't be exceeded, but I dunno about Chinese equipment.
I wouldn't have much confidence in a small air regulator installed on a pressure pot. Those small ones with a body diameter of about 2" are generally very poor at regulation.
Latex paints are generally abrasive, with fairly coarse solids in them. These solids can erode the paint needle, tip and other internal parts of conventional spray guns and most types of spraying equipment.
Paint pots were typically used in applications where the painter would be applying fairly large volumes of paint, so s/he wouldn't need to be waving a quart of paint around with the arm extended, and to reduce the the time needed for refilling a cup. The pot could be held with the other hand with that arm hanging straight down, minimizing overall fatigue of the gun operator. The paint delivery hose only needed to be about 6 ft long when used in that way.
The 2 quart size pots were often used in autobody shops where a complete overall car refinishing job could be completed with 1 refill.
The pot guns were typically left connected to the pot, and cup guns or touch-up guns were used for lesser applications. Disassembly would encourage wear on the fittings causing leaks, so regularly adapting the gun to cup use wasn't very practical.
Pot pressures would generally be low, since the pressure only needed to supply a consistent delivery flow of paint to the gun head.
It's also important to keep the pot exterior clean, since dried paint buildup can eventually find it's way into the pot, causing job interruptions and other problems.
As mentioned previously, it's important to filter all contents of the cup or pot, and very worthwhile to use clean strainers on the pickup tubes as a sorta failsafe against clogs or other issues.
Sputtering in a siphon cup gun can be due to a restriction in the cup cover vent as suggested, or the needle seal on the trigger side. I don't know what causes sputtering in a pressure pot setup other than the paint delivery rate is too slow.. but that seems unlikely unless the paint is being applied so heavily that the pot can't replenish it quickly enough. Even a decent quality siphon cup design can keep up with any application rate, so I don't know why a pressure pot wouldn't, except for if the ID of the supply hose is too small, since you mentioned about a 15 ft hose length (liquid being denser than air, a larger diameter may be needed).
Maybe an air leak above the paint level in the pot, which might allow air to be injected into the paint flow (Chinese equipment, suspect anything).
--
WB
.........


"Existential Angst" < snipped-for-privacy@optonline.net> wrote in message
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It's got one.

Not precision, dats f'sure.

That explains why the Husky gun got 1 star from a guy who complained he had to keep re-buying them, due to deteriorating spray quality. He said they all worked great initially, but after a few months, deteriorated. Sounded like he did a lot of painting!!. I wonder if professional guns use hardened nozzles?
Are the nozzles in Husky-type guns (typical siphon gun, I suspect most of them are generic) replaceable? Across brands, mebbe?

I gotta get one of these. Mebbe I can scavenge the Wagner filter. :)

I'll have to experiment with this. I"m using crap HF 3/8 id air hose. Lowering the viscosity of the paint would help, and if I have to make to too thin, that's an indicator that the hose diam is too small.

Very possibly!!!! Air leaks at the pot lid are very audible, and it is indeed a bit of a pita to stop them at each clamp. I may have in fact been a little *too lax* on this. I'll watch for this next time.
--
EA





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I didn't see your reply thru my APN news feed.
All conventional paint guns I've seen utilize replaceable fluid tips/nozzles, generally following a model or series of a particular gun model. Some gun producers began fabricating the fluid head (a separate part from the handle assy on better quality guns) and tips from stainless steel when latex paints started gaining popularity.
The gun needle and fluid tips need to match in size, and some gun producers market numerous sizes to accomodate different re/finishing products. Optional air caps are available with more/fewer or differently sized atomizing ports, also for various products. The air caps generally need to match the fluid tips for a particular model/series.
I suppose that hardened needles and fluid tips are available for production line spraying equipment, but don't know of any first hand.
Strainers that slip-fit onto paint equipment pickup tubes are readily available from paint and autobody supply sources, and are commonly used routinely as an added prevention to avoid problems with finishes.
Examining the exploded view/parts diagram of a paint gun will reveal where the seals belong if it should need to be disassembled for thorough cleaning etc. The parts list may also include optional parts mentioned above.
Routine inspection of the tip of the needle can help determine if the needle and fluid tip are becoming unuseable. In lower quality gun designs, the needle drags as it enters/withdraws from the fluid tip, increasing the rate of wear.
--
WB
.........

>Existential Angst wrote:
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