Dust and Primer

I just got done with my 2nd primer session on the tail. While I fixed the disaster from last time (orange peel out the ying yang), I am noticing that I have some dust specs in the primer. I am using the 2 part Akzo mil spec primer. I am too lazy to build a paint booth. Question: Will these dust specs inhibit the corrosion protection of the primer in a significant way?

I'm about done with the 2 part mil spec primer. What a PITA!! It's just very difficult to work with. How does the Azko that Spruces sells compare to the mil spec stuff?

Let's see another primer war...YEAH BABY!

Jay

What kinds of problems are you having?

If you don't like 2 part primers there is always 3 part primers.

I think the AKZO spruce sells is to a MilSpec developped for Boeing, I believe. It's to a Boeing spec, at any rate. All MilSpec means is that there's a specification for performance (or size, shape, color...whatever) so that you can order MilSpec BladdidlyBlah from any manufacturer and you know exactly what you're getting. There's plenty of MilSpec stuff out there - primers, hardware, electronics, etc - that ain't worth a darn....but it does conform to the spec

Unless what you're using is much different from the formulation Spruce sells, there should be no dust in the primer unless you're putting on a very heavy coat. In any sort of reasonable weather, it's tack free VERY quickly.

Regardless, the dust shouldn't hurt anything assuming it got there after you sprayed. If you just sprayed a dirty piece of aluminum, which I'm 99% sure you didn't, it's a different story.

The stuff I am currently using dries in about 2 hours. I'm pretty sure the dust got there after I sprayed and it looks kind of bad, but as long as it does't hurt anything...I'm not going to worry about. I may switch to the Spruce stuff since it dries about 10x quicker.

Jay,

This may not be a factor here, but it might so I'll say it anyway.

When I was spraying on some primer during a motorcycle painting project, it looked like it had a bunch of dust on it after it dried. However, what I learned is that it was really caused by the overspray as I was moving around the very curved pieces. As an aside, it was a 4-part process on the motorcycle -- Variprime primer, Fill-n-Sand primer - (sand) - base color - clear coat.

So, what I started doing was angle the gun a bit so that most of the overspray is headed towards the un-sprayed part of the piece. That way, my next pass would coat the over-spray and leave it the way it was supposed to be.

I hope this makes sense. And I don't know if this is what's happening to you or not. Especially since the Fill-n-Sand primer dried really fast, and you say that your version of Akzo dries in a couple hours.

As a data point, I am using the Spruce version of Akzo and really like it. No problems at all.

-Jim

Too thick?

Jay the 2-part Akzo stuff Aircraft $pruce sells is to a Boeing specification, and it dries tack free quickly (in minutes), as stated above.

I confused how you could have got orange peel with it in a previous application. The paint is meant to be applied in a very thin layer, barely covering the aluminum. If it's just right, you can just make out the "grain" in the aluminum through the paint, but no direct silver color of the metal is visible.

Could you be applying the primer in too thick a layer?

What are the part numbers on the cans?

gil in Tucson

Gil, probably all the above. I think I am spraying it too thickly...and that was probably due to incorrect settings on the gun. 10P20-13 is the number if I am not mistaken. The instruction sheet says a closed even layer for the painting.

I actually got recommended the stuff from the paint guys on the Air Force base. I watched them primer a t-38 and they put a solid layer on the jet. Is that wrong?

Different stuff

Jay.... the number you mentioned is a low volatility Mil Spec primer and is quite different from the Aircraft Spruce stuff.

The data sheet is here...

http://www.anac.com/products/DataSheets/10p20-13.pdf

The 2 hours tack time is correct... this alone will make it hard to keep dust free....

It gives this mixing ratio...

3 parts Base 10P20-13
1 part Cure Solution EC-213
0.5-1 part Optional Thinner: TR-114 or TR-49

Since it's a low VOC primer, you might find it easier to paint if you add some volatility back into it with the optional thinner...

They do recommend one coat only, and it should dry to a pretty thin 0.8 to 1.0 mills.

You can search for on-line copies of MIL-specs here...
http://assist.daps.dla.mil/quicksearch/

So..
1. Are you using the thinners?

2. Are you mixing in the correct ratio?

gil in Tucson

10P20 is good stuff. At work I have a can of 10P20-44. It's a really good self-etching primer. I used it on all my torque tubes in my RV-8A. For good coverage all you want is an even thin coat. Thinner than you would apply a coat of paint. If you are painting over this primer, the dust and orange peel you are getting can be mostly removed by lightly sanding with 320 grit paper.

Not self etching

KTM520guy said:

10P20 is good stuff. At work I have a can of 10P20-44. It's a really good self-etching primer. I used it on all my torque tubes in my RV-8A. For good coverage all you want is an even thin coat. Thinner than you would apply a coat of paint. If you are painting over this primer, the dust and orange peel you are getting can be mostly removed by lightly sanding with 320 grit paper.

Click to expand...

KTM250guy (huh?)

The 10P20-13 is MIL-P-23377 primer, and may be good stuff, but it is not self-etching, if that is what you are inferring above.... It needs etch and alodine first.

Your 10P20-44 is not self etching either...
Manufacturer's data here - etch and alodine first...

http://www.anac.com/products/DataSheets/10P20-44.pdf

gil in Tucson

I stand corrected. In my defence though, when the Akzo rep came by and asked what we needed I just said "send me over a kit of self-etching primer". This is what he sent. Still, it is a very good primer. Cost was a little bit more that what I'm already using and doesn't perform any better. I saw no reason to switch. I have used that can of 10P20 on a lot of my personal stuff with very good results.

Tack Cloths and filters.

I watched my painter do my RV.
He filtered every drop of paint - though I didn't bother with the primer.
He always had a 'TACK CLOTH' in his hand and wiped everything immediately prior to painting.
If you don't have a booth it is worth wetting down the workshop floor to stop any dust rising whilst painting.
Pete.
PS. He was an RAF trained aircraft painter. How lucky can you be.

Thanks for all the help guys. It didn't turn out too badly. I'll just sand the dust away with 400 grit sandpaper where there are mating surfaces. I will get some tack cloth and wet the floors next time.