Troubleshooting Fine Flecks in Paint

Finishers try to figure out the source of tiny solid flecks in a batch of paint. November 11, 2006

Recently we have been getting flecks of something that look like small pieces of either pigment or metal in our ML Campbell primer and paint. We strain our paint before using it, but this stuff seems to get through anyway. I noticed when we strain it that there is definitely more sediment in the strainer. Have any of you found this to be true recently? We have not had this problem with their product in the past and are just trying to find out if we received a bad batch or if this is a recent problem.

Forum Responses
(Finishing Forum)
From contributor J:
We had the same problem one time. There were little multicolored flecks in the paint. The distributor said that they hadn't thoroughly mixed their paint and we sent it back. That was about three years ago.

From contributor R:
Pour a little finish right out of the can on a piece of glass and let it dry in a dust free area. If there is grit in the finish, then it's either the manufacturer's fault or you used one of those metal agitators on a drill motor and grinded off the can lining into the finish. If there isn't any grit, then it could possibly be contamination in your spray system. You can check that out the same way.

From contributor W:
You didn't say what kind of primer and paint you are using, only brand name. Is it solvent or waterborne? And also type of equipment you're using.

From the original questioner:
The products we are having the problem with are Clawlock and Resistant, both solvent base, catalyzed products.

From contributor S:
It sounds like you're not cleaning out your sprayer good enough. If you're using a system with hoses, keep them filled with lacquer liner at night.

From contributor M:
We get trash in ours occasionally. We solved it by finding the source. The problem only happened when I used a cup gun. Never happened when I used an airless pump. We use MLC's CVs. I mix them in the quart cup, but my gravity feed HVLP that I use for onsies and twosies only holds 2/3 of a quart. So when I pour the mix in, there's a bit left over in the plastic mix cup.

The trash was from the skin that then forms on the side of the cup. When I pour the remainder of the CV into the gun hopper, I was peeling some of that skin off and it was so very, very fine grit that it was going straight through the strainer. Looked like little pieces of pigment, flatting agent, or something. But it was partially cured varnish boogers.

We solved it completely with this two-step process:
1) I only catalyze 20 oz (easy 2 oz of cat). This will all fit in my HVLP gun. I then rinse the cup and set it aside.
2) I bought some fine-mesh paint filter material from Lord and Evans. Big gallon-bag sized filters, but very fine mesh, much finer than a funnel paint filter. I cut each in half and lay it inside the funnel filter when I pour the CV into the gun. I do still see the occasional fleck, but I believe it's flatting agent clumps this time, and it never makes it into the gun.

From the original questioner:
We run thinner and a cleaning agent through our hoses every night and we strain all paint and primer. We have not had the problem before... only in this last 5 gallon pail. That is why I was wondering if anyone else was experiencing the same problem. The flecks, when looked at with a magnifying glass, appear to have a black speck in them and occasionally one will look like a small thread from steel wool, although we don't use any steel wool in our sanding process. The other odd thing is that we are getting clogging in the gun filter... almost like it is gumming up, which we have not had before. We use a filter on the end of the dip tube and put a strainer bag additionally over that and this stuff is still getting through. I am going to try to put a cleaning solution in the lines tonight and I will let you know if it helps.

From contributor W:
Seems to me that you have done and checked everything on your end. And if it hasn't done that before and just started with that five, I would draw the conclusion that the problem lies within that five. Have you tried any other fives?