I just went to shoot color in a friends booth and cannot determine why I am experiencing a major problem. I was shooting the underside of the hood, the inside of the door and the tops of the running boards. It is Omni single stage urethane over urethane base primer. This is the same system on the cab, nose/grill, inner fenders and bed that I had done previously without any problems.
What I am experiencing is that I get spotting/fisheyes or lack of adhesion like you would get like from silicone contamination. It also tends to be more susceptible to runs. I no longer will use Prepsol after a bad experience with it 5 years ago. The pieces were wet sanded with 500 and then washed with a very mild soap solution and clear water rinsed with a hose. I even used his bucket, soap, rags and water supply that he uses. This is the way that my friend that has the paint booth preps for color. He paints regularly and has not had this problem.
When I painted the underside of the boards, probably about 6 weeks ago, I did not have the problem. The hood and doors have been in my shop however after painting the underside of the boards they never were back in my shop. They went directly from the same paint booth to a spare bedroom in the house.
It is a fresh gallon of paint which is one thing different. When I painted the 4 pieces of the hood hinges/springs, I did not experience the problem. They had just been sandblasted and primed within 72 hours of shooting color. The other pieces have been in prime for varying longer lengths of time.
The metal and shop temperatures were 65-70.
My friend that owns the booth and I are both baffled!
Anyone out there that paints cars for a living or a lot had a problem like this?

 

I am NOT a paint expert but i do have a fairly strong chemistry background. A lot of lube sprays WD40 etc, rubber dressing, leather and vinyl dressings, waxes and polishes, even cooking sprays, contain silicones, and they stay airborne and travel for quite a while. Soap and water WILL NOT wash away silicones (that's the major reason they put them in waxes)! There are better more modern silicone removers than prepsol, ask your paint store for one compatible with the paint you are using and ask if they recommend a fisheye preventive to be mixed into the paint. If the primer has aged, I would give it a fresh overall light wet sanding using the prepaint prep as the paper lubricant. Always wash and dry with new clean shop towels from a fresh sealed package. Keep the opened package of towels in an airtight container while in storage. Since most laundry detergents and fabric softeners contain silicones, and fabric good manufacturers give new fabrics, especially terrycloth and jersey (T-shirts), a liberal spray of silicone before shipping to increase the fluff and reduce lint pickup, so laundered shop towels or using new home store towels can introduce problems.

 

It does sound like a wax or silicone contamination problem .
What type of soap did you use to wash it down , I hope it wasn't a car wash type stuff containing wax ??

 

Most likely the soap, wash mitt, shop rags or towels as said. You need to be using a good wax&grease remover......I use PPG DX330 0r 440.

Could also be oil/water in the air lines or even in the gun.

Guy I worked for years ago was painting a car in the booth when his wife decided to bring her car into the shop to clean it.......started spraying Armour All on the dash, etc.
It totally ruined his paint job.....he was one PO'ed dude.

 

I have painted vehicles for over 40 years professionally and have never used soap and water on a wash down. After wet sanding, wash with clear water and dry the parts with an air gun, soaps do have silicones in them. Also don't touch any part to be painted with your hands as you will get body oil on the part, as bad as silicone. Just prior to painting wipe lightly with thinner , wipe with a tack cloth and add some fish eye eliminator to your paint. Shoot everything at 50 psi. (eliminates orange peel) My 2cents.

 

Thanks for your replies. I am becoming increasingly concerned that I have a case of silicone contamination. I am guilty of bringing DOT 5 into the shop. Absolutely the wrong thing to do. Unfortunately my shop does not have an isolated body work/priming/blocking room.
If it is silicone contamination what have you done to thoroughly clean the final primed surface short of stripping off all paint and filler? What little reading that I have done indicates that water or lacquer thinner will not remove the silicone. I read that alcohol with a ton of rags is supposed to work.

 

Try this: Dow Corning® OS-2 Silicone Cleaner and Surface Prep Solvent is a volatile methyl siloxane (VMS) fluid that is compatible with a wide range of materials. It will not harm most substrates, including plastics. OS-2 can be used to remove silicone-based; greases, oils, car wax and car care products, will soften cured silicones to facilitate removal.

 

Thanks for your response. I have been cleaning with TSP. I would also like to get and try the OS-2. Have you used it successfully? It does not appear to be available through my typical paint suppliers. I did find it (no longer available in small-like a pint size) through a machinery supply house where I get unique seals ans bearings when I need them. The smallest quantity is pushing $100. Where have you bought it?

 

Well compare that to the cost of repainting the contaminated surface, and I'll bet 100.00 will be a lot less, especially if your labor is worth anything. The lesser of the evils.

 

Bill,

I have never bought any but I did use some that a friend gave me (he is a paint and body man) and it worked well - no fish eyes.

Good luck with it.

 

A couple observations...500 grit is too fine for pre-paint prep, I use 320-400 to ensure a good tooth for the paint to bond to. Secondly, whenever I have issues with fisheyes I can usually trace it back to the air supply. More oil comes through the compressed air supply than any residual oil/wax/silicone found on the surface, especially after the surface has been wiped down with pre-prep/pre-paint wax and grease remover. I have seen guys wipe the surface prior to paint with a quality W/G remover and fail to follow the wet wipe with a dry rag to pull up the residue...this will just redistribute any contaminants on the sanded surface.

 

My buddy and I had this same issue, almost like the paint would just bead up or run off when we tried to paint his car outside. Few weeks later we moved into a guys paint booth and had the same issue. He had saw it before and used a fisheye eliminator, added it to the paint, and had no issues after that. Worked amazing. I don't know the brand he had but a quick search came up with this....

http://www.eastwood.com/fish-eye-eliminator-pint-eastwood.html

Good luck and hope you can solve your problem.

 

Thanks to all again for your input. I do not believe that the problem came from either my air system or my friends with the booth based on other evidence. I really believe that one of the rags used was the culprit.

Charlie, You do raise a good question about the 500 grit and "tooth". I had thought about that. The cab and bed do show some sand scratches. I had dry sanded those area with 400 prior to color. 400 I am sure would be fine if I was shooting 2 stage and buffing out the entire truck. Willard will not be a show truck (I am a driver and don't do shows) and will pull a car trailer like he has in the past and not ride in one. All of that said, I do try hard to get a good quality finish. Obviously I could drop back and wet sand those areas with say 400 wet.

My next step is to try some color test spots on areas inside the doors that will get upholstered.


I am not sure how to handle the heavily fish eyed areas on the underside of the hood. It has one coat of color. I suspect that I need to remove all color in the fish eyed area. My thoughts were to wet sand that area using the TSP dosed water as the water to wet sand with, your thoughts?

I do want to use fisheye removal additive in the paint if I can since my understanding is that really just makes one big fisheye out of the paint and I do not want the potential of having to always use it in the future.

 

IMHO not using fisheye preventive in the paint is like not buying collision insurance. It saves a few bucks, but you sure wish you had it right after the accident. YMMV.

 

Sadly there is only on way to fix a heavily fish eyed area, sand it down until you have a solid base and shoot it again. Fisheye additive may help your problem but the root cause of the problem is still there, the additive just masks the problem. Hopefully you can find the source of the contamination.

As far as surface prep I prefer to shoot color on a little smoother surface. After the final coat of primer I like to hit the surface lightly with 320 dry and then use 600 wet and then shoot a nonsanding sealer before color. This might be a bit of over kill but on some darker colors it will show sanding marks if your surface is to rough. I know that giving the paint a surface to bond to is important but I have not had any paint fall off a vehicle yet.