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Can't shake the trash

#1
About two years ago I painted an F350 with SPI B/C, came out excellent minus the orange peel. Very little trash that I remember. Fast forward to this Mack I am doing and I have trash everywhere. I do a sealer of 1:1:1 then three coats of Nason SS (another topic for another day). The surface texture is excellent out of a SATA 5000, minus the consistent trash that gets everywhere.

I have a stick framed, plastic walled (and taped) booth, with filtered air coming in making positive pressure, just like I did two years ago. I filter the sealer and paint, clean with both cleaners (6+ hour wait time after), tack panels, tack the stands, tack the gun, cup, and line to the floor. Today I sprayed in a dirty shirt and shorts, and ended up with the same result I did when in a tacked off suit. The filter is a CT30 which is brand new, along with a brand new flexzilla hose, new bulb filter, and clean gun. This trash appears both during spraying panels and also if I just shoot a concentrated spot on a scrap panel outside the booth, and most of it occurs when spraying color (NOT SEALER). It looks like very fine sanding grit but is too small to really judge without a microscope.

I have sprayed just air into a clean towel and get no visible contaminates. Besides throwing in a coalescing filter or tracking down much finer strainers, I am about at wits end because, there is just too much of it, unless I am like PigPen from the Peanuts. Thoughts?
 

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#2
About two years ago I painted an F350 with SPI B/C, came out excellent minus the orange peel. Very little trash that I remember. Fast forward to this Mack I am doing and I have trash everywhere. I do a sealer of 1:1:1 then three coats of Nason SS (another topic for another day). The surface texture is excellent out of a SATA 5000, minus the consistent trash that gets everywhere.

I have a stick framed, plastic walled (and taped) booth, with filtered air coming in making positive pressure, just like I did two years ago. I filter the sealer and paint, clean with both cleaners (6+ hour wait time after), tack panels, tack the stands, tack the gun, cup, and line to the floor. Today I sprayed in a dirty shirt and shorts, and ended up with the same result I did when in a tacked off suit. The filter is a CT30 which is brand new, along with a brand new flexzilla hose, new bulb filter, and clean gun. This trash appears both during spraying panels and also if I just shoot a concentrated spot on a scrap panel outside the booth, and most of it occurs when spraying color (NOT SEALER). It looks like very fine sanding grit but is too small to really judge without a microscope.

I have sprayed just air into a clean towel and get no visible contaminates. Besides throwing in a coalescing filter or tracking down much finer strainers, I am about at wits end because, there is just too much of it, unless I am like PigPen from the Peanuts. Thoughts?
Have you considered that the ‘trash’ may be in the paint itself, pigment kick out or something like it that only shows until you spray it? Have you tried spraying any different clear or other SS just as a test that your air setup is clean? Sorry to hear about your troubles.
 
#3
I have the same problem and from what I can see of your booth it looks of similar construction to mine. I think its the plastic walls, holding debris and dropping it when air is moving in the booth. Ive tried several different ideas of my own and what Ive read and haven't had much luck. I nearly rebuilt my booth but didn't as I'm about half way done using it now.
 

Chris_Hamilton

Trying to be the best me, I can be
#4
For a home booth using hardboard aka masonite board is a much better solution than using plastic. Light frame in with 2x4 and then 4x8 sheets of masonite. Around 10-14 bucks for a 4x8 sheet depending where you get it.

Here's what I would use if constructing a home booth. Light frame in with 2x4's and this stuff https://www.homedepot.com/p/1-8-in-x-4-ft-x-8-ft-Eucalyptus-White-Hardboard-447562/204727075

Mount a fan, seal the seams with cheap caulking, make a exhaust pocket with 2x4's, you could have a nice reusable booth for around $500-600.
 
#5
Pour some of your mixed paint on to a sheet of glass and see if it's clean.
I got that once from a flattener that was old, the specs were to fine to filter.
 
#6
For a home booth using hardboard aka masonite board is a much better solution than using plastic. Light frame in with 2x4 and then 4x8 sheets of masonite. Around 10-14 bucks for a 4x8 sheet depending where you get it.

Here's what I would use if constructing a home booth. Light frame in with 2x4's and this stuff https://www.homedepot.com/p/1-8-in-x-4-ft-x-8-ft-Eucalyptus-White-Hardboard-447562/204727075

Mount a fan, seal the seams with cheap caulking, make a exhaust pocket with 2x4's, you could have a nice reusable booth for around $500-600.
Lighting would certainly be a consideration in any type booth, and the plastic see through may be better in that regard, but what about minimal lighting in your suggested hard board booth and then this light on the gun? Has anyone used one of these?
https://www.lumaiii.com//home/products/aurora
 
#9
I helped a friend out once who got rear ended in his 41 Packard. I sprayed some of the Chromabase he had left over from the origional paint job. It had gone bad and looked like it had super fine sand in it.

I use plastic without issues and would suggest that you look closely at trash being blown out of crevises, your clothes, or air hose if it is not bad paint or catylist.
 
#10
I sprayed some epoxy today using all the same prep, no change. Sprayed some random SS on paper outside, no change. Cracked open the bulb filter to see if it had anything in it, nope.

I just can't accept that there is enough dust floating in a garage to create my issue.
 

Chris_Hamilton

Trying to be the best me, I can be
#12
Are you tacking immediately before you spray and between coats? Is the part you are spraying completely clean? If yes are you sure? Sounds like you are getting trash from the part. Escaping from crevices underneath etc. Is the trash even across the panel or here and there? If it's even it's something in the paint. I have seen trash in basecoats because of a toner that has gone bad. Happened to me a month or so ago. We had a bad aluminum toner and it left what looked like trash all throughout the paint. If it's not happening when you seal than I'd start looking at other things than airborne contaminants. If it's in the paint you will not strain it out.
 

Chris_Hamilton

Trying to be the best me, I can be
#13
It also could simply be airborne. Just because you didn't have any trash before and can't see any trash floating around does not mean that there isn't any and it's not getting in the paint. Being you are not in a real booth simple airborne contamination would be my first guess. The atmosphere on the day you shoot can have a lot to do with it. Windy dry days more trash, calmer more humid usually less. Next would be the part itself. Those are the most common. Less so is the hose (internal) although a dirty hose on the outside can transfer some trash. Keeping a tack rag in one hand while you hold the hose when you are spraying is a good idea. Even some of the cleanest booths out there get trash in them, so expecting a homemade booth to be surgically clean is unrealistic.
Edit: Looking at the pics are you getting any lifting from the plastic masking? Do you have the correct(treated side) out? Is it refinish grade plastic or regular hardware store plastic? If it's backwards you could be getting dry overspray bouncing off the plastic and back into the work. It will look like trash. If it's not refinish grade stuff you'll get lifting which could be going back into the work. All I got without laying eyes on what you are doing.
 
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#14
I tack sealer. I don't tack anything that's going to get sanded. I'm anal like no other when cleaning. Gloves. Solvent, water, solvent. Extended dry time. Everything tacked except the walls. Plastic is whatever Home Depot had on the shelf. I've tacked the plastic randomly and get only very fine overspray. Parts don't have any crevasses. Vacuum booth, new suit. Only visible skin is around my eyes. Shop is insulated, constant temp. Doors always closed, no vehicles in or out ever.

Trash is consistent. I sanded some nibs in one area and came up with white (sealer color). I doubt there's anything wrong with the epoxy but I'm going to open a new set and see what it does. I wish I could find super fine strainers, 190 micron is a large hole.
 
#15
I guess I see a booth as an engine. Oil pump sends dirty oil through filter, engine gets clean oil. Force only filtered air in a confined space, dirty air gets replaced.