Hello guys
I'm having problems with ML Resistant, wonder if someone can help us out. We are using Kremlin 10/C18 pumps, 15psi air and 30psi fluid,number 6 tip, Spraying Resistant, 10% catalyst, 20% Lacquer thinner, with 3 to 4 wet mills, after spraying you can see a bunch of tiny little bubbles, mostly goes away, but some stay ruining the finish. We've try 15% Thinner, 25% Thinner, we also try with 5% flow Enhancer, we've try remove the screen from the #6 tip, tried #9 tip, raised the fluid Psi to 40, 50 , we've check for air leak, we've tried everything that we can possible know, no success, but the funny thing is we just sprayed a bunch of doors and some pieces of crown at the end of the day, the doors come out with some bubbles but the crown come out perfect, same batch of product, very strange. Really appreciate any help, Thanks

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What is temperature/humidity?

Stealth was made to be used in an AAA pump since Resistant had issues with the shear action of a Kremlin style pump.

I don't have an answer for you on the Resistant, other than to switch over to Stealth and have little to no problems.

Temperature on the low 70's and humidity around 80%. Leo have you ever used Resistant? just wonder your thoughts between the two, thanks

I started using Resistant long ago, Stealth didn't even exist. I never had luck with it. Always something to go wrong and never a glass smooth finish. The first time I got a great finish out of Resistant was on plastic.

It would always do the same thing. You'd spray it, it would bubble up incredibly, and then you could watch the bubbles just disappear. But never all of them. I switched over to MagnaMax line for my pigmented stuff.

Then they came out with Stealth and I tried that. 1st time I remember spraying a flat slab drawer front. I sprayed it and I waited for the bubbles, nothing. Flat as could be. And it kept happening over and over. Early versions of Stealth had separation issues in the cup so you had to make sure you agitated it frequently. But they fixed that.

So now all I use is Stealth. I think Resistant is a bit harder and it sanded a bit easier. But the Stealth is a good finish and much easier to work with. I've come up with a thinning formula that seems to work under most all conditions for me.

If you don't get bubbles on one piece of wood, but you do on another, then the paint can't be at fault. Are the parts that have bubbles veneered or MDF by chance?

Ed, we also use Stealth with a Kremlin 10-14 pump, 09 tip. pump at 45 lbs. 15-20 0n the air to remove tails. We are in Calif. so we use the 275 Stealth with 5% catalyst, 10 % retarder or Flow #2 if humidity is high. hold gun at 12-15 " above surface. The retarder allows the solvents to release before surface hardens over. Good luck, we had trouble this summer for 2 months, tried everything and one day the skies cleared and we were back to normal,LOL. ML Campbell claimed nothing on their end, material, colorant.

I have never worked with that product, but was wondering what your wet mils of product is. A lot of the time solvent pop happens when your material is sprayed to thick and your air has no where to escape, I would try spraying it thinner, you may have to ad an extra coat to get the build you want.
The other thing to try is a different catalyst, or ad a retarder so the product has a slower flash time.

I have never worked with that product, but was wondering what your wet mils of product is. A lot of the time solvent pop happens when your material is sprayed to thick and your air has no where to escape, I would try spraying it thinner, you may have to ad an extra coat to get the build you want.
The other thing to try is a different catalyst, or ad a retarder so the product has a slower flash time.

something else to consider. it might be residual sanding dust (trash). i have struggle with what i thought was solvent pop or mystery bubbles for seemingly forever.

i had an experienced finisher doing some temporary work for me so he gets the credit. he wipes the surfaces off with his hand after he has blown a piece off. the glove reveals a lot of dust still on the piece. i have been doing the same for six months now and the results have been back to near perfect. over the summer we're high temps with high humidity an spraying only 2k poly, so i'm pretty sure i was experience trash in my previous struggles.

one other thing, we used to scuff with 320g, blow off and recoat. now, in addition to wiping by hand as a last step, i hit with 320 followed by maroon scotchbrite. the scotchbrite seems to help break up the sanding dust the 320 creates and gets if off the surface. i don't always dust the bottoms of panels off by hand and have been getting very nice results with this extra scotchbrite step.

good luck.

Thanks for all the replies guys, this is really driving me insane here, we just tried another method from another finisher, no success, not even my local ML rep. can give me a straight answer.

We use a Kremlin pump and had the same problems you are having with a few of the ML Campbell products both clear and pigmented. It was a constant but intermittent problem we were never able to solve. We switched to Chemcraft products and have had very good luck with their products.

If your ML Campbell rep can't sort it out you might consider a new supplier.

I 2nd the hand wipe down method, it defiantly makes a difference in getting the last dust off. I keep going over the piece till I feel all the dust is gone. As Leo G stated switch to Stealth, we spray it here daily out of AAA setups with consistently good results .

It's not the paint, it doesn't know where to solvent-pop, and where not to so don't blame the paint or the supplier.

I took a closer look at your picture, it looks like trash, not bubbles, have you tried wiping down the piece with alcohol? This helps eliminate a static charge that may be on your surface. Give this a try.

Brian, I know it's not the paint, I'm not blaming the paint, and yes I am blaming the supplier for coming to my shop, spray a piece himself and still having the problem and not coming out with a solution. What you see in the picture is tiny little bubbles, after we spray, 90% goes away, but some stay, it is "Not" trash, we clean our product very well prior to finish. thanks for the Reply

In the case of Resistant it is the paint and the combination of shear of the AAA pump. It was a known problem that they fixed with a new product. I don't thing the CAT pump produces the same shear.

Leo is correct, I run CAT pumps and don't have a problem with Resistant. I just prefer Stealth

Don't know if this is it, but try switching out your Thinner for Butyl Acetate. That seems to work for us in our MLC products in what I think you are describing. Can't explain it...but it has worked.

Butyl Acetate is the first ingredient in MLC Reducer and Flow Enhancer #1

Here's a different perspective. I don't see anywhere in this thread where anyone suggested using a primer? Hardwoods will accept a topcoat with little difficulty, but MDF is a whole different animal. Also, it looks like you're trying to build in excess of what your coating is made to achieve. MLC makes a product called Clawlock. It's a catalyzed surfacing primer. Apply 2 coats, sand and topcoat with your resistant, 1 to 2 coats to achieve desired appearance. Most AAA units operate at 20 to 30 PSI in both air and/or fluid pressures, you determine what works best for you. 15 PSI air and 30 PSI fluid indicates excessive fluid, meaning the fluid is coming out faster than the air can atomize it, so you're throwing material on. If you want to use topcoat only, then try lighter first coat, sanding, then heavier coats. Resistant shouldn't "require" thinning, especially with an AAA. By your picture...it appears that you sprayed a very heavy coat, it dried slowly from excessive wet mills, and caused an extreme grain raise on your MDF. Clawlock would resolve those issues

I hope this was helpful

LacquerdUp, thanks for the reply. Clawlock is the only primer we use for the last 5, 6 years. I mention all my pump settings on the OP. MDF? never mention I'm having problems with MDF, we are spraying 3 to 4 wet mills, "not heavy" at all. Thanks again for all the help from everyone here, we've come out with a solution for our problem: 10% Lacquer thinner, 10% #2 flow, tip #4 and fluid between 25 to 30 psi. thanks again.

I wonder if it just needs a little thinner. Solvent evaporation happens quickly and lacquer that is too thick can do that. One of my contractors just encountered a similar issue and thinning it resolved the issue. Just my 2 cents worth.

Hey Edi, my formula for Stealth is a 2:3 ratio of #2:Reducer. I mix up 20oz of #2 and 30oz of Reducer in an old thinner can and then just use that mixture as my thinner. I do 20% for Stealth.

I find it much easier to just premix the thinners then all you need to do is measure it out of the one can.

Thanks Leo, that's a great idea of mixing g the two together.