Bruce

Bruce

Well Known Member
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Can anyone tell me what is going on with this primer. It is EP 420 and I am getting all kinds of stuff in the setup. I do have a paint booth that I try to keep clean. I had to use 400 sandpaper and Scotchbrite pad to take down and the final paint looks great. Just wandering what this problem is.
Thanks,
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Are you wiping the surface down with a tac rag before shooting? Are you pouring your primer through a strainer before putting it in the spray gun? Is your paint booth dusty? If possable, wet the floor down with a hose when your spraying.
 
Strainer

I will do the strainer. Most of the particles were in the paint cup. Just had it happen with one batch so I don't know what it was. Will do the wipe down with tack cloth. Most of the time I use MEK and wipe it down with lint free rag. This is the only timed it happened so I was checking if maybe it was bloom but didn't know what that was. I DO no what orange peel looks like though.
Thanks for the suggestions !!
 
Bruce said:
Will do the wipe down with tack cloth.
Click to expand...
When wiping with the tack cloth, do it lightly (like dusting) - putting pressure on the cloth will leave some of the tacky resin on the metal. You don't want that!
 
tack cloth

Ambient dust can travel into the paint from many sources which includes dust on shelves where no air is passing over. It has something to do with the electrical charge in the air.

I use my work shop to paint but I clean (blow off) the shelves the day before. Then cover the shelves with plastic so the charge in the air doesn't suck remaining dust off the shelves. Dampen the floor (like previously advised), use tack cloth from a auto body supplier (not Harbor Freight), strain, and have a final dryer before the regulator which is right at the gun. Cheap regulators will vary with compressor pressure so get a good one that retains the desired pressure irrespective of compressor pressure.

Wash the fluorescent lites the day before so they're bright, and make sure the air coming into the booth passes thru an air filter to purge the air of dust

Practice before squirting. That's what former wife's cars are for.
 
Inlet Vent

I did turn off the inlet vent for fresh air and it did seem to help some. Thanks for all the advice. Isn't painting soOOOO much fun.

Good luck,
 
If you are using Polyfiber EP 420 you're putting way too much on. This stuff is almost transparent when applied. It does not coat and build up like most primers. One medium cross coat is all that you need. White looks like gray over AL. I used Polyfiber EP 420 White on my 7A. What color is that? I know they have White and Green. And Yes, always strain your paint.

Roberta
 
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Hidden dust

Remember to mask open areas on whatever you're painting. For example on the wings be sure to mask the open ends because dust has accumulated inside and will be sucked out when you spray.
 
I don't think it's dust.

I am going out on a limb here but I bet your top coat is a urethane finish.

I am also going to guess that the "EP" product is an etch prime.

If this is the case, you skipped a middle step. You didn't SEAL the primer.

The bubbles are air being trapped under the top coat because the primer was not sealed.

:( CJ
 
See this thread here.

It is my paint test thread. My experiment is holding up well. It has not been washed or waxed since it was applied and looks brand new.

;) CJ
 
I want to make sure I understand what I'm looking at. Is that paint or primer? If I understand you correctly, it's primer with lots of defects. You say you sanded it smooth and painted and all was well. If I've got this all correct I'd say it looks like solvent popping. If you lay certain finishes on too heavily without waiting long enough between coats, the evaporating solvents get trapped under the "skin" formed by the next coat and make lots of little bubbles. When in doubt, read the data sheet for the product your using. :)
 
contaminated primer

These types of materials are catalyzed and if the catalyst and material are not mixed in the right ratios part of it will coagulate out and leave the clumps that you see. i have seen this happen with materials that are old also. Strain the material through a ladies stocking and it will filter out most of the coagulate. I dont think it is dust unless you have an absolutely filthy painting area. I had this same type of a problem once shen the catalyst got too old. I have an old referigator that keep all my catalyst type materials in to preserve their shelf life.

I taught auto body and paint for 25 years and always see new stuff. you never know about paint materials.
 
My 2 cents

Cold paint, humidity, and air that gets colder yet as is comes out of the gun can do some wierd stuff. :confused:

All the previous advice sounded helpful too. I would try again another day with all the new found knowledge. Some times there is more to Experimental than we thought we were getting into.

But have fun and let us know what you learn. :)
 
Do you have the data sheets for the product? I am sure it needs either a primer sealer OR a primer AND A sealer.

Wet sanding and top coating like you did is a fine resolution, but to avoid this in the future and to paint "light"... use the sealer.

;) CJ
 
I am going to have to agree with Bill on this one. It is primer and it is put on per specs as 1 light coat followed by 2 med coats. It was happening after I mixed it and it was in the cup. Should have run it through the strainer first then the problem would be nill. Any way the top coat went on perfect after I sanded the bumps off this primer. I just wanted people to see some of the effects of wrong primer applications. My problems. Thats why I like this sight so much.

Thanks again for all thoughts !!!!!
 
Bruce, looking at the expanded pic of the primer it looks like lint/dust and not enough care in tacking.

All have been mentioned but one thing I might share is a trick I learned in the prep process before any primer including wash primer is applied.. This takes very little time but the results are worth it. Noting the smiles around your rivets indicate a rejection of paint due to impurities and it will carry on throught the whole process. I have built and painted a Rv3,4,8, Stewart Mustang and getting ready to paint my second Rv8.. Used the Pro-Seal process each time.

Try cleaning surface with mek and using a dry cloth before the mek evaporates. I then squeegie good old Pro-Seal into the rivet line and let sit for about 20 min and wipe off with mek. Use Gloves..
I then use a light coat of wash/etch primer followed by a primer for the final coat to attach to.

My first posting and hope this helps

Rod

Filling the rivets sounds like alot of trouble but it results in time savings and alot less fillling/material applied to achieve a good finish.
 
Rod, please explain

rodbower said:
Try cleaning surface with mek and using a dry cloth before the mek evaporates. I then squeegie good old Pro-Seal into the rivet line and let sit for about 20 min and wipe off with mek. Use Gloves..
Click to expand...

Rod, If I understand this right, are you using pro seal as a filler around the rivets? Or, is this a way to promote adhesion for the primer to follow?

Barry
 
Are these nibs showing up on the underside of the panels, And areas where dust could not fall down in to it?
80% of the dirt in a paint job, you bring to the surface, on your clothes, in the paint gun etc etc.

Sometimes "cleaning" a paint gun, dont mean its really clean. The residue left behind by some thinners will cause some materials to ball up like that, usually that stuff only happens in a small area tho, same as the dirt on your clothes.
More likely your mixture is not right for the conditions, too slow or too fast reducer, wrong hardener or too little reducer etc, basically it looks to me as though the primer is drying on the aircap, and being blown in to the wet paint, a chunk at a time.

Do you have a REALLY good water trap and and particle trap? The **** comming out of even a brand new aircompressor will blow your mind, Chuncks of rust, oil, and bits of sealant from the lines, and pump itself.
 
Re: Proseal rivet lines

Prosealing the rivet lines will make the rivets look more flush after painting, less of the little dip. Adds marginal amounts of weight though...
 
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