Troubleshooting Tiny Hair-Like Fibers in the Finish

A finisher seeks advice eliminating contamination by small hair-like fibers. August 16, 2012

I've developed a serious problem. I'm getting tiny black hair particles which show up mostly on opaque topcoats. I've completely cleaned out the spray booth, changed the exhaust and air intake filters, everyone is now wearing full body suits, and I'm still getting these tiny hairs on my finish. It's driving me crazy and I can't get rid of them. Any help?

Forum Responses
(Finishing Forum)
From contributor J:
Maybe from your hoses? Do you have a filter at the gun?

From contributor D:
Could it be residue or parts of whatever you use to sand or rub out the under coats? I've seen steel wool and Scotchbrite pads leave hair behind, and if not blown off, they may still be there.

From contributor M:
You only have two possibilities: Either from your material or from your environment. If you spray out your material on a piece of glass you should be able to isolate that issue. The environment is just a matter of removing all possible options. If you set a clean piece of glass on your spray table, turn your booth on and leave it there for as long as you would normally leave a wet piece, one would think that you should find the same hairs on the glass. If so, check where you are drafting air from. In the past I have shut off the booth fan, set up a few pole push fans in the opposite direction as the booth draws, and blown out the area with a good leaf blower. Then hosed the whole area that your booth draws from with water. Also wet mop your floors down and check for anything blooming outside your doors. In the past I have even gone so far as to make door size filters out of 1.5" PVC sprinkler and upholstery Dacron (comes in 8' rolls).

From contributor A:
I once poured a new 5 gallon bucket of white lacquer through an ultra fine strainer and the strainer became plugged with tiny red hairs like you describe. When I am about to spray a quart or so on a critical job, I will use 2 or 3 of those cone strainers. At a previous shop I worked at, the finishers were known to sabotage each other's material by dumping things in their lacquer. Anyway, straining your material will tell you if those fibers are in the lac or not.