Gun Kote problems, twice now. HELP!

[ScottsGT]

Any Gun Kote experts here??!!
Trying to get some input here before I call KG coatings tomorrow. But I have painted the aluminum frame on my OACP twice now. I keep getting bubbles in the finish, almost a wrinkle paint appearance, but only in the same place each time. Around the half moon cut outs behind the trigger.
I sandblasted the exterior of the frame, second attempt I buffed the blasted surface down with 0000 steel wool since I could see too much texture of the blasting. I airbrushed on about 4 to 5 good coats using a high end airbrush, but I did not use a hairdryer between coats as par the "Brownells" video.
the before baking example looked great. Comes out of the oven looking like hell though.
BTW, I'm also not too happy with the "Satin Black" finish. It is actually gloss, even after shaking the can for 3 minutes.

 

[MAX100]

It is best applied on a anodized surface.


GC

 

[gb6491]

No expert here, but did you degrease the steel wool or degrease the part afterwards?

Another thought; how long are you letting it dry before putting it in the oven?
The solvent in the coating needs to be fully evaporated before the heating process. If it isn't you will get some blow through as it heats up and the solvent becomes a gas and escapes. Even with the heat drying betweens coats Brownells is recommending a 30 minute cure time.

Regards,
Greg

 

[ScottsGT]

The solvent in the coating needs to be fully evaporated before the heating process. If it isn't you will get some blow through as it heats up and the solvent becomes a gas and escapes. Even with the heat drying betweens coats Brownells is recommending a 30 minute cure time.

Greg,
I think you are an expert! Come on out of the closet, you know your paint. I took a closer look, and it looks exactly like solvent popping. We used to get the same thing with laquer paints on cars (about 25 years back) when we got in a hurry.
I'm going to give this another shot, pun intended, later this week. Here's a photo of the mess.

 

[jarhead]

This is how you learn... you try something new, if it doesn't work quite right you dig for the solution and then try again. Each time you get a little wiser for the next time around.

 

[funnelcake]

I thought they recommended 1-2 light coats of the stuff?

 

[DnPRK]

My wife has side by side ovens that I get to use when she isn't home (and won't find out what I'm doing ). I pre-heat the part to about 100-120F in one oven before applying a couple very thin coats of Gun Kote. By the time I walk back indoors to the 305F oven, all the solvent has flashed off. The part goes straight into the 305F oven for an hour cure.

 

[jarhead]

From my experience with applying GunKote, I think you are pre-heating the parts too hot prior to applying the finish. That appears to be bubble up from the solvent in the GunKote boiling off before it can evaporate. If you look at the areas affected, it appears to be edges of holes in the frame and in the areas of most dense/solid metal content (i.e. the upper part of the frame, at the top of the mag well has the most "meat" to retain heat). Most kitchen ovens that I've seen have a hard time maintaining a heat at the 100-120 degree mark and my guess is that it is over pre-heating the parts for the finish to apply.

If you have ever seen a 1911 frame that has been case hardened, the brilliant blue hues mottle with the reddish/tan/gray hues into a mosaic... this is indicative of the way different areas of the mettle have retained the heat during the hardening process. The areas on your frame appear to hold a similar pattern of case-hardened areas that would be more bluish (having retained more heat in denser areas being hardened).

This is only based upon my experience and opinion... YMMV.

 

[ScottsGT]

I'm actually preheating with a heat gun. One used for shrinking MonoKote film coverings for R/C Aircraft. It's warm to the touch, but not real hot. I'm thinking my main problem was too much paint, and too heavy application. I come from the old school of autobody painting where we had to find a happy medium of just wet enough to not run. After talking with KG's rep, he too thinks it is the solvent popping from too much material applied. He also told me lighter mist coats should make the paint more satin as it should be. They offer the black in gloss, satin and matte.
Maybe this evening I'll get a chance to blast it all off and reshoot.
Paul, I'll give you a call this afternoon on my way home.

 

[dogbaloo]

You have orange peel. You still have some oil on the surface that has not been removed. I am not a painter, but I grew up in a house with one! Aluminum is tough because it is a little more porous and can trap some residue. Make sure you completely degrease the part and DO NOT HANDLE IT.

Good luck!

 

[ScottsGT]

Orange peel is not a result of oil on a surface. That would be fisheyes. Trust me, I was an autobody repairman/painter for 10 years and I have many showcars that won awards for my work. The surface was as slick as glass before baking. The surface was VERY clean and untouched. Although, GK told me they get better results from washing the part and not wiping it down.

 

[gb6491]

Scott,
Thanks for the kind words earlier.
Your post about talking with the GK rep reminded me of something.
I use the aerosol cans of gun kote. When putting on the last coats, I did them from quite some distance hoping the paint would atomize a little more or at least bigger blobs (for want of a better word) would not reach it. Kind of like a controlled over spray or dusting of paint. Here are some links to the results (the second is after about a month of carry):
http://gbrannon.bizhat.com/1big.jpg
http://gbrannon.bizhat.com/2big.JPG
Regards,
Greg

 

[ragntag]

cleaning parts

try cleaning it in boiling water first with some baking soda....
i did this on a blueing job for my ak receiver i then used a cold blue to boot. and it came out great
i just put it in the hot soda/water for about a minute or two, when pull it out the part will be hot, pores in the metal will open releasing any oil/dirt. the water will evaporate off. a clean rinse of water you might want to have next then some compressed air to finish dry any hidden pockets of crap in those tight spots then put your custom finish on, part will be warm and dry to accept your paint. and not overheated.

 

[moredes]

This ain't orange peel; ScottGT's right about that. It's definitely not oil (or any silicon "type") contamination either--those kinds of contamination would produce fisheyes, as Scott also said.

I'd say it's just very, very slightly possible the part was too hot before painting; but I'd lay those odds at 5%.

More likely, Scott laid it on too thick and dried it too quickly under heat. It's just as likely too much heat alone (above) the recommended temperature was used. That, by itself could have force-dried the paints and produced the solvent-popping.

No amount of paint (counted by any means desired--thickness/number of coats) is too much so long as there's not so much paint that it can't cure properly. It is possible to put on so much paint (measured in thickness) that the paint "never" dries, and any amount of paint is too much if the surface is dries ("skims over") before the substrate dries completely--the slow version of this (force-) drying phenomenon is "wrinkling"; the fast version appears as this does--solvent-popping.

As an aside, I, too, have read from several sources (gunsmiths' posts [Vickers, CT Brian, Christiansen]) that aluminum should be anodized as a requirement to alleviate problems of inherent softness in the metal.

 

[ScottsGT]

OK, I got it this time! Airbrushed on 4 to 5 very thin, dry coatings. allowed 10 min. between coats and flash dried each coat with the heat gun. Gave it 30 to 45 min. drying time before baking. Turned out GREAT!!
I'll post photos of the finished product when the plated parts come back from Tripp.
Thanks for the help guys!!