[billnotgatez]

Are your studio mates into pranks?


“ When you have eliminated the impossible, whatever remains, however improbable, must be the truth?” — ...
Sherlock Holmes Quotes

[Corribus]

I think you may then want to explore the paint as your cause. As Enthalpy noted, paints are very complex mixtures, and pigments or other components could be crystalizing before or during drying. Have you tried some different batches or types of paints to see if this phenomenon is consistently appearing?

Are these new paints or old paints? If they're old, paints don't always age well. If they're new(ly purhcased)... they could still be old unless their manufacture date is indicated.  Even then, you don't know how they were stored at a warehouse or during transport. And even if they were stored as intended, there still could be manufacture formulation error.

Just some things to think about. Although I do not do professional painting, my daughter loves art and old paint, particularly those that have been opened, can be chunky or gritty.

[billnotgatez]

Do you observe this grit while painting or later as it is drying or has dried?
You might have answered this but I may be missing it.

Never mind I reread

You notice it while painting.

[Ovalman]

Corribus,

It is not the paint. I can actually see particles of sand (they are beige-colored) attach themselves to my wet surface, say a dark blue surface, over the course of a few minutes. I've been painting for over 40 years and taught college/univ. art (drawing and painting) for 30. I know paint. I'd post a picture of these particles on a wet painted surface but would have to send one from my phone to my laptop. Clearly these particles are sand, along with some other debris remaining from the building's sandblasting (pulverized pieces of brick, wood, dried paint and bitumen—"pitch," which was used as a floor covering/adhesive back when buildings like these were built). I've already identified these contaminants and they are external to the paint.

I opened my windows yesterday and the humidity in the room increased to about 40% (I have a humidistat in my studio, although not a very good one). I also directed a box fan away from my immediate work area toward my suspended air filtration unit. The higher humidity seems to be solving the problem—which supports my theory, as unlikely as it seems, that the very low humidity in the space has been causing my wet paint to attract these particles. I'll know more as the warm days continue. My studio has been bone-dry since last fall.

I wish you all could see this problem in person! You'd plainly see what I'm talking about.

[Ovalman]

Also, Corribus, as I wrote yesterday—you may have missed it—this sand (and debris) alights on my clean white palette surface as I'm mixing paint, seemingly drawn by the wet paint. So it's not even in the paint, just next to it.

[Ovalman]

Here is a picture of a painted surface, roughly 4" x 4". The blue is the wet area which immediately attracted the debris you see within it. The largest grains are about the size of table salt. The debris is 90% sand. (Many of the tiny white spots are white paint showing through the blue paint. You can see shadows under the actual grains.) Sorry I didn't post this at the beginning of this thread.

[Ovalman]

Looks like no one else is responding to this thread. Thanks to those of you who have.

Since, as Enthalpy concurred, the grit particles are too heavy to remain airborne, I can only conclude that a force is attracting these particles to my wet paint over intermediate to far distances. The only force I'm aware of is static electricity, apparently made extreme by very low humidity during these cold months. Although Enthalpy says this would be "nearly magic," no one has put forth an alternative explanation.

Seems fitting to conclude with billnotgatez's Sherlock Holmes's quote: "When you have eliminated the impossible, whatever remains, however improbable, must be the truth?”

Granted, my grit problem is not as interesting as a murder mystery.

[Corribus]

Hi Ovalman, sorry - I just don't have many other suggestions. Something like this may be hard to troubleshoot theoretically. Probably best approached experimentally - try to change up some of your experimental practices (one at a time, keeping everything else constant), observe the result, and try to hone in on what the cause is. This is standard practice in any experimental science. My first experiment would be to use all the same materials and methods but in a different environment and see if the problem persists. This is the easiest way to prove that it's an environmental issue and not a problem with your supplies or technique.

[Borek]

Problem is fascinating, sadly, next to impossible to troubleshoot remotely.

[Ovalman]

Thanks for your replies. Corribus, I know what you mean about experimentation. Having painted in enough previous studios, I have an empirical foundation against which to compare. The only variables in my current studio are the residual sand/grit from the sandblasting, and variable humidity. I know I could move my location and not have this problem—I've never had it before. But I'm not in a position to move my studio.

So I sort of know what the problem is; I was hoping someone would corroborate my "theory" that static electricity is the only force that could be acting upon these grit particles to attract them to my wet paint. I certainly have been conducting (no pun intended  ) "experiments" since last fall by installing an air filter, removing carpet (that might harbor grit) from my floor, etc. The only variable that seems to make a difference is the humidity. I'll report back when, in a month or two, the higher general humidity because of warmer weather "solves" the problem.

My only other option is to remove the source of grit but this would be very hard to do entirely.

Thanks again for indulging all my lengthy posts!

[Ovalman]

One other piece of information that might bolster my static electricity theory: when I set my reading glasses down on a work surface, after a minute or so the plastic lenses "fog up" with a fine, slightly splotchy, light gray film. So does the blue plastic top of my humidifier. This doesn't appear to be water condensing on these surfaces (such as when you walk into a warm room from the cold outdoors and your glasses fog up); I believe it's a coating of micro-dust particles (or a mixture of micro-dust and fine water particles).

I did some reading about static electricity—negatively charged surfaces and positively charged surfaces and how they react. We know plastic surfaces often possess a static charge, apparent when you remove a piece of cellophane from a package and it sticks to your fingers.

Does the fact that my reading glasses attract micro-dust suggest that the room humidity is low enough to produce a static-rich environment, so much so that my wet paint surface can attract extremely dry particles of grit?

[Ovalman]

Here is another painted surface; this detail is about 50 square inches (roughly 7" x 7" or so, considering the perspective). Hundreds of particles; the largest are the size of table salt.

Again, these particles do not appear on any of my flat surfaces—floor, desk, work table—so they're not continually falling from the ceiling. They're too large to hang in the air. They appear only when I have a freshly painted wet surface.