Waterbased surfacer / primer clogging spray gun.

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Ever since I've started spraying this Sherwin Williams surfacer (used to just use their self priming product), I've had problems with my fluid passages in the gun slowly solidifying. After about 30-45 minutes of spraying I have to do a complete gun strip and clean. It's like it turns to jello or starts to solidify in the fluid inlet, around the needle and in the fluid nozzle. Cleaning is difficult too, due to it's solidifying nature. Anyone else experience this? I'm spraying with a high-end Trans-Tech Devilbiss, gravity fed gun with their deKups system, 1.4 set which sprays great until the gun's inner passages plug up. Gun has stainless steel fluid inlet and anodized passages, which I believe from the Devilbiss sales literature may also be stainless steel.

Luuuke

use bigger nozzle set. i like a 1.8 for primer

Stephan

Member Member

Just to clarify, its not the needle and fluid tip that are plugging up, its the main fluid passage from the cup to the fluid tip that are turning into a solidified glob of jello. Eventually (in less than an hour) it gets so built up that no more fluid flows from the cup to the tip and I have to strip the gun.

I'm working on ordering a 1.8 set for it as I think it will help the overall spraying of the primer, but I don't see how it is the cause for what's happening up in the gun.

Luuuke

oh wow! lol. yeah that doesnt sound good. ive never heard of that myself. but a bigger nozzle set wont help that....

Adam

This is a strange one. I've sprayed a couple of drums of wb thru guns and pressure pots that are aluminum. Never a problem. Occasionaly when wiping out a pressure pot the rag gets a little dark from the finish oxidizing the alloy. That is product dependent. Never had the insides of a gun get clogged like you are describing.

Does the gravity gun you are using have one of those little filter things?

Is the wb primer catalyzed or the viscosity of drywall compound?

Stephan

Member Member

I'm not really sure about the catalyzed part, I don't think Sherwin Williams clarifies on that, but it's about half the viscosity of a common household latex paint. I use the DeKups which have a large 3" diameter filter right at the cup outlet where it enters the gun. I will try to take a picture next time.

Kevin

I use sherwin williams products exclusively and have never ran into a issue like you describe. What is the product code of the surfacer your using? The primer i use from sherwin is E63W50. This is Kemvar Surfacer. Catalyzed product. Very good stuff. Probably the best primer ive ever used.

Stephan

Member Member

Kevin, thanks, I'm using Kem Aqua Plus Surfacer E64W520. I could be mistaken, but I'm fairly sure that the Kemvar product line is not water based but is solvent based, is that correct?

Kevin

that is correct. Kemvar is a post catalyzed product.
I have used a fair amount of kem aqua on projects in the recent past.. More and more customers are requiring low voc for their LEED projects so we explored waterbase as an option. I did not like the dry time. But i used the same surfacer that you are having a problem with, except i did not have the issue your describing. I think a call to sherwin williams tech will reveal a bad batch, but thats just my opinion. Sherwin has some of the best techs in the business in my opinion. Atleast in my neck of the woods. They come right out and get to the bottom of any issue. Give them a call.

Kevin

^^^ Post catalyzed SOLVENT BASED product, excuse me.

Mike Fuson

I've been spraying Chemcraft's Aqua prime and have pulled up some clumps that didn't get agitated good enough but I've not had it to jell in the gun like you describe, actually never heard of that. If it were me I would thin it with some water and we also use some cheap little funnel type screens from the hardware store that work great for filtering out the occasional clumps.

Stephan

Member

I should clarify, the gelling only happens on rare occasions, but the difficulty in cleaning the gun and gradual build-up with this stuff is constant. I have a thought about the gelling / cottage cheese, it's like air is getting into the fluid chamber somehow. I have ordered some new parts for the gun on the thought that something might be nicked and the material is drying / setting up in the fluid passage because air is being siphoned through it. The DeKups strain very well, so I don't think its a straining issue. Our S/W rep up here is not easily accessible.

Evan

Member

You may have a small scratch somewhere in the anodizing..Might be all it takes. Maybe this surfacer is even more corrosive than the other WB materials.

Steve Smith

The emulsion is being broken, and the oil-phase is being forced to separate from the water-phase and coagulate with itself. That the surfactant being used in manufacture is failing is an issue to take up with the manufacturer.

That said, reducing the flow velocity of paint thru the gun will reduce the problem. Making the emulsion more dilute (adding water) will also reduce the emulsion breakage under the mechanical stress of higher-velocity flow, particularly if it is transitioning from laminar to turbulent flow inside the gun.

Stephan

Member Member

Steve, thanks for the information. Since replacing some gun internals I have yet to have the gelling issue resurface. Either I got a bad batch or there was something amiss in the gun. I am now warming this surfacer prior to spraying and have gone to a larger needle set and I'm finding that this is working well. This surfacer is tough as nails though, cleanup sucks. Immediate water rinse and then thorough cleaning in straight acetone is the only thing that works for a proper clean.

Do you guys get build-up around your fluid nozzles like this? Its a consistent issue with the primer, less of an issue with pigmented lacquer and not an issue with the clear.

View higher quality, full size image (2448 X 3264)

Mike Fuson

I sprayed a five gallon pail of Aqua prime today, and yes clean up sucks. I had to stop and clean my gun several times. I used to use Mohawk ez-vinyl primer and never had these issues, but the Aqua prime is cheaper and covers much much better. I like it good enough to keep cleaning the gun I guess. One thing I did start doing just today, I bought a 100 count of dekone strainers made by devilbis for about 15 bucks. I strained the primer from the bucket to the gun every time I refilled and my gun sprayed much better.

Stephan

Member Member

It happened again. This time I got a picture, although it's hard to see. Blocked flow to about 25 percent. Gun was freshly cleaned and first cup and it has this problem within the first pass. Material is being filtered at deKups fine, something in the gun is happening. Re cleaned gun and was ok after that. Major pain when it happens.

View higher quality, full size image (3264 X 2448)

Stephan

Member Member

It happened again. This time I got a picture, although it's hard to see. Blocked flow to about 25 percent. Gun was freshly cleaned and first cup and it has this problem within the first pass. Material is being filtered at deKups fine, something in the gun is happening. Re cleaned gun and was ok after that. Major pain when it happens.

View higher quality, full size image (3264 X 2448)

Mike Fuson

Just curious, how much of this material have you sprayed? Is this the first pail ever of this particular product? Or is this something you've done for some time? Just wondering if this is a characteristic of the product or you got one bad pail? Don't blame you a bit for getting frustrated with it, hard to get anything done when you have to stop and clean!

Stephan

Member Member

I've been spraying this product for quite a while, having gone through multiple pails, and it's been one of those issues all the way through. It's so strange how it turns to the consistency of jello in the gun which makes it very difficult to clean. Interestingly I used the same cup full of product, same filter, changed nothing on that end and it sprayed fine after another cleaning. I noticed that when I clean my gun in acetone after it will congeal the primer in the wash container I used into the same type of consitency. Later on I put a little acetone in the gun then put the cup with fluid on and sprayed, thinking it might have been residual acetone causing the issue, but all that happened was it sprayed a touch thinner, like it had been reduced.

I was thinking last night, since I hot pot my product, maybe the warm primer hitting a cold gun would have something to do with it, but then after the second cleaning, the gun was cold again from the evaporation of the acetone and it didn't happen. I also tried running some air into the gun by inverting the fluid cup and spraying until the liner in the DeKups had contracted enough to start picking up fluid, then sprayed for another minute and stripped the gun, didn't see a hint of gelling. It's really got me stumped.

Mike Fuson

I don't think the warm/cold would have anything to do with it.
Acetone will make the stuff gel for sure, as will lacquer thinner, I have found that every time I go through a cup If I spray a couple once of water through the gun before filling back up it seems to keep the gun flushed. The only time I use acetone is at the end of all the spraying and I've done cleaned with water good. With the stuff I use, which is chemcrafts aquar prime, you can stir it with one of those things that goes in a drill for a long time and it will still have to be strained to spray it.

Stephan

Member Member

Mike, today I've been flushing with water between each cup and before using acetone and cleanup has been much easier, thanks for that tip. The Kem Aqua surfacer is pretty clean, but I still use filters as well.

Mike Fuson

Good deal man, glad to help!

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