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Pressure pot spraying. A couple questions.

4/5/17       
LazarusLong

Hello, I am new to the pressure pot world. I have a C.A.T 2.5 gallon pot, with their H2o gun... I am spraying Hydroplus pigmented waterborne. The spec sheet says that this stuff is 17-22 secs in a zahn#5 cup. This is the thickest material I have ever tried to spray. I thinned it with 8 oz of water per a gallon of finish. Still too thick. I added another 6 oz. Now It will spray, but the pot pressure is close to 20 psi to get it to come out of the gun. The spec sheet recommends 5-10psi.. The finish also just doesn't seem to want to flow very well... Do I need to thin this stuff by a lot more? Maybe 15% of so? Any help is much appreciated!!

4/5/17       #2: Pressure pot spraying. A couple que ...
kevin

what size fluid nozzle are you using? Ive not had an issue like you're describing. I dont used a pressure pot, but that shouldnt be the problem.

I use gravity feed and also AAA with the hydroplus and it sprays out wonderfully.

4/5/17       #3: Pressure pot spraying. A couple que ...
LazarusLong

Thanks for the response. I have tried all three tips, 1.7, 1.5, 1.3... So, when you spray this stuff, does it flow out nicely after a couple mins? Its not doing that for me... It seems like I have to spray a heavier coat than I want, or it won't flow at all. I already feel like the air is up too high, as i'm producing a ton of over spray.

4/5/17       #4: Pressure pot spraying. A couple que ...
kevin

Turn the air pressure down. You dont need much atomization. Too much air will cause it to dry up before it gets to flow out.

4/5/17       #6: Pressure pot spraying. A couple que ...
Lazarus Long Member

What air pressure are you running your gravity feed at?

4/5/17       #7: Pressure pot spraying. A couple que ...
Rick Mosher

17-22 seconds in a zahn #5 would be about like trying to spray peanut butter. Most pressure pot systems work best at around 20 seconds in a zahn #2 cup. In my experience adding water to WB finishes is never a good answer.

To set up a pressure pot, turn off the atomizing air and pull the trigger. You should have a stream 2 to 3 feet long. If it is longer you have too much fluid pressure, if it is shorter you have too little.

If I was going to spray something that viscous I would go up to a 2.8 to 3.0 size fluid nozzle.

With WB finishes most of them need to be sprayed with a tack coat on the first pass and then the second pass can be heavier, the slow drying should allow the finish to flow out so more atomizing air is not a good answer either.

You will have to do some experiments to get it to work. I haven't used that product so maybe someone will chime in who has. Can you get a tech rep to show up at your shop?

4/5/17       #8: Pressure pot spraying. A couple que ...
Bart

I use GF's line. There undercoat is really thick and I can usually spray it right out of the can with my pot setup. Some batches are thicker than others so I do thin sometimes which as Rick mentioned isn't always a good idea. If I don't thin it I'll warm it up real good for max viscosity. You can't go real fast or a wide fan but it works fine for cab doors/drawers etc. What I've started doing in some cases is shooting their clear sanding sealer first which shoots great, then one coat of thinned undercoat so the added water doesn't affect the grain much, then two topcoats.
I shoot more on feel rather than by what the gauge says. I've 50ft of hose then the pot+ 10 more ft to the gun finally. So I crank the compressor about 10lbs past the max incoming pressure and crank the outgoing pressure from the pot to max and final tune at the gun with the adjustable built into the gun. Not a bulky in line pressure gauge.
An airless or a AAA sounds like an option with that brand. What the heck it's only $$$

4/5/17       #9: Pressure pot spraying. A couple que ...
LazarusLong

I did talk to the rep. He thought it sounded like the stuff wasn't atomizing properly, and to turn up the air. He said he is 45-50 psi air pressure for this stuff when he has sprayed it. I just sprayed a couple things with increased air pressure, and it seems to have sprayed better.

What I don't want to happen is for finish to build between the door stiles/rails and the panels. If I have to spray too thick of a coat, that will certainly happen..

We'll see how the rest of the day goes. If i'm still having issues the rep said he was willing to stop by and help to troubleshoot.

4/5/17       #10: Pressure pot spraying. A couple que ...
Adam

All of the waterborne finishes I've sprayed are fluid set to 12-20 and air 40. I start at 12 and turn it up until I get a nice beer piss. More like the six pack variety not the two beer kind.

We stick with the 1.5n/n unless its a heavy body primer like the MLC. The can weighs more than drywall compound. The 1.7 works with those.

Unless the can litterly says add X amount of water, do not add water. Do not add more.

4/6/17       #11: Pressure pot spraying. A couple que ...
Lazarus Long Member

Thanks for the replies. I have been experimenting. I started with a new can, pumped up the pot pressure til I go a 2' stream, and turned up the air til it just started to atomize.. So quite a bit less air than I was using. Not much overspray now.. The atomization certainly isn't what you get with a AAA, but I guess that's how these guns work?

4/6/17       #12: Pressure pot spraying. A couple que ...
Lazarus Long Member

Well this is making me crazy.. The finish just refuses to level out nicely. I'm looking at stuff I sprayed a few hours ago, and the finish looks lumpy. Not like orange peel, but more like really shalow dimples. Not fisheyes either.. The only part of the door where it leveled nicely is the inside profile. I tried to take a picture but my camera couldn't focus on it very well.. What is going on here?


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4/7/17       #13: Pressure pot spraying. A couple que ...
LazarusLong

I guess I'm talking to myself here now, but I think i'm on the right track.. While it isn't necessarily cold in my shop, 68-70 or so, air temp, which means that the finish in the pot on the ground, is probably closer to 60ish. I warmed up a gallon to around 80 degrees, sprayed it, and it definitely leveled out better.. I'm considering putting a small heating blanket/pad under the pot for tomorrow.

4/8/17       #14: Pressure pot spraying. A couple que ...
Adam

One of the best things I ever did in my spray room was to take an old broken refrigerator and ripped out the glass shelves. Replaced them with melamine ones. Spaced for gallons and quarts. My stains go in the door. I bought a digital thermometer and a small 5" cube ceramic heater/fan. I keep all of my finishes & pva glues at 75 degrees. The fan heater hardly ever runs because of the super insulated box. Its good for epoxy in the winter as well.

I keep the solvents with the vodka in the freezer. My old shop got down to freezing in the winter and was heated with a forced hanging gas heater. I was always concerned about the wb and glue freezing.

4/8/17       #15: Pressure pot spraying. A couple que ...
nick

After reading the thread I understand the problems with this primer.The question I found myself asking is; what are the up sides to using it? It seems to me changing to a different more workable primer is a easy answer to the problems with using this product.
I use the old tried and true pigmented shellac for priming my pigmented WB jobs and it works great; sprays great, dries fast, sands easy and stops any grain raise. The obvious downside is it's solvent based.
I have a dedicated pot/gun set-up for it as it is hard to get the fluid line super clean; Devilbiss 504 with 410 aircap, 1.3 needle/nozzle, 8psi fluid pressure, 29psi (2 bar) atomizing air pressure gives me perfect results and little to no drama.

4/8/17       #16: Pressure pot spraying. A couple que ...
kevin

nick.... the hydroplus is not primer. its topcoat. and i think laz is on the right track. cold weather definitely affects viscosity. Need to warm your material to get flow.

4/8/17       #17: Pressure pot spraying. A couple que ...
kevin

i would like to add that your substrate should be at similar temperature to your paint

4/8/17       #18: Pressure pot spraying. A couple que ...
nick

whoops,I just assumed at that viscosity it had to be a primer.But the question still begs to be asked;if it's this much effort and results are less than acceptable, what's the up side to using it?...I'm having a hard time wrapping my mind around using a 2.0 or larger N/N with a product and calling it a 'fine finish'.

4/8/17       #19: Pressure pot spraying. A couple que ...
LazarusLong

I'm using it because its a formaldehyde free, waterborne finish. Its also greengaurd certified. I'm hoping that it is better for me and the environment... At the shop I used to work at, the conversion varnish that was used was just as thick as this stuff...

4/8/17       #20: Pressure pot spraying. A couple que ...
kevin

i use it all the time and have not experienced any issues.
It must be our 80-90 degree weather year round but this stuff works great for us.

4/8/17       #21: Pressure pot spraying. A couple que ...
Lazarus Long Member

Moderate improvement today. Still not great, but I think it will pass after it tightens up..

@kevin, are you self sealing with this stuff, or going over primer? I did prime everything first.. I hope that isn't the issue. If it is then I'm kind of screwed at this point

4/8/17       #22: Pressure pot spraying. A couple que ...
Lazarus Long Member

Here's another question. If the problem is with the primer, (SW universal) after sanding the first coat of HP, it should flow out over itself like it's supposed to?

4/9/17       #23: Pressure pot spraying. A couple que ...
Lazarus Long Member

Just as an experiment I mixed 25 ml butyl carbitol 25ml water into 400 ml finish.. Sprayed a test panel.. Other than having to turn the pot pressure down, it didn't seem to make the finish level any better... I'm wondering if there is something wrong with the product.

At this point I have one coat primer and two coats of HP on everything.. Im feeling like I might need to call it quits with this stuff... But now what? I have to give my customer a good product..

4/9/17       #24: Pressure pot spraying. A couple que ...
kevin

i would suspect the product to be bad.
Yes, we prime our stuff first.
If i were in your position i would call SW and tell them you need immediate technical support. If their tech rep cant get it to spray properly then the product is no good and they need to replace it. So at that point either they give you a good batch of hydroplus or you can just finish the job with Kemaqua


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