Tamiya Paint Issue

[DeanF]

Hi, lots of great paint jobs here, I hope someone can tell me what I'm doing wrong with Tamiya spray paint. On the first coat of Tamiya White Primer, spots developed where the paint pulled away a bit. This occurred on the model prior as well, although it was with Metallic Blue on that one. I did search but could not find this particular issue with Tamiya paint. Similar discussions lead me to think it's contamination, but the bodies were sanded, washed in water with Dawn, thoroughly rinsed with clean water, then handled with nitrile gloves. This has happened occasionally in the past, but two in a row now make me think I'm missing something. I'm not exactly new at painting, but I sure would like to learn how to avoid this in the future. I appreciate any advice. Attached an image of the spots on the roof.

 

 

Edited March 14 by DeanF
Swapped image

[iamsuperdan]

I would guess the body still had mold release agent or some other contaminant on it from the production process.

But you said you washed it.

 

Hmmm...odd.

 

[peteski]

I wonder if those are fisheyes? Those are often caused by traces of silicone contamination.  Did the primer pull away in those spots, down to bare plastic?   The body might need a wash in something stronger than Dawn.  You could try 91% Isopropyl alcohol.  But stay away from Rubbing Alcohol - it has additives.

I assume you will strip the primer.  That process itself might be enough to wash away any contamination.  I'm also wondering if there is something in your nitrile gloves causing this?

[Bainford]

That's fish eyes, caused by some type of contamination on or in the plastic, despite the cleaning. It needs to be stripped and cleaned with a more aggressive cleaner. 
 

44 minutes ago, peteski said:

 You could try 91% Isopropyl alcohol.  But stay away from Rubbing Alcohol - it has additives.

Rubbing alcohol is isopropyl alcohol. The only additive is water. 91% isopropyl alcohol is rubbing alcohol that contains 91% isopropanol and 9% water. 

[1972coronet]

2 hours ago, peteski said:

I'm also wondering if there is something in your nitrile gloves causing this?

That was my first guess.

[peteski]

2 hours ago, Bainford said:

Rubbing alcohol is isopropyl alcohol. The only additive is water. 91% isopropyl alcohol is rubbing alcohol that contains 91% isopropanol and 9% water. 

Not always.  Some brands of rubbing alcohol also contain other (lubricating) additives for easier rub-downs.  Better to just go for the bottles labeled "Isopropyl alcohol".   And yes, I'm aware that (likely distilled) water is added to dilute the IPA to whatever strength it is sold at.

[Ace-Garageguy]

Looks like fisheyes to me, as stated earlier, the result of surface contamination.

And it's not just silicone that causes it, but many kinds of lubricants, mold-release agents, wax, etc. I've even seen pollen in the air cause it.

My guess is that something used in the production process of your gloves, or on the gloves, is the culprit.

Dishwashing detergent may also have chemical anti-spot additives that can cause fisheyes.

I'd suggest, as I always do, a final cleaning with 70% isopropyl alcohol just before you shoot anything. I use the cheapest white paper towels, as they don't seem to have anything in them that causes a problem.

And you don't need to use gloves while working with iso. It IS, after all, rubbing alcohol.

EDIT: I started using a final iso cleaning after a few nasty fisheye episodes while painting real aircraft, where a problem like this can cost thousands in material and labor to correct.

After I started using iso, no more problems on real stuff or models.

 

 

Edited March 15 by Ace-Garageguy

[Mothersworry]

You mentioned  that after cleaning the body you handle it with nitrile gloves, it's possible that the gloves may be the source of the contamination. Nitrile gloves are available in powdered, lightly powdered, and unpowdered.

These powders are typically corn starch based but may also contain other stuff including silicones. Most nitrile gloves are not "clean" gloves intended to protect what you touch but rather protect the wearer from whatever they are touching.

Archival nitrile gloves are available and are designed specifically to protect what the wearer is touching from contamination. 

Just a thought. 

[Dave G.]

I've gotten this even with using alcohol, so my final rub down of the model now is as I did in shooting 1/1 paint jobs. I switched my final wash to wipe the surface down with liberal amounts of odorless mineral spirits. And I've never gotten it since.

The gloves are a real thought as well. So is sneezing over the model. If it were an airbrush being used it could be contamination in the lines from the compressor, but you said it was spray cans.

[bobss396]

I have never used gloves to handle models being painted. Read the box, maybe they have a silicone product in them? 

[stitchdup]

I dont think it is the gloves. there just isn't a pattern from handling in the fisheyes. If it was the gloves i would expect the fisheyes to be more concentrated where the model is being handled. do you have one of those plug in automatic air fresheners? it wouldn't have to be in the same room as it carries in the air and it can easily get on your clothes by walking past it.

[DeanF]

Hey, I really appreciate the replies, thank you! Lots to think about and I'm now re-thinking of everything that had contact with the body. I will say though I tend to agree that the gloves are probably less likely to be the source since yes, the body was handled all over with them and the spots are only on the roof. I actually masked off the exterior with a plastic bag and masking tape, so there are two more potential sources. In addition to that I used a tack rag kept in a sandwich bag immediately prior to spraying. I like the idea of wiping down with isopropyl alcohol or mineral spirits, what do you use to wipe it with that won't leave lint? I believe prep is the foundation for a successful paint job, so I'm still open to any suggestions. No air fresheners, and spray painting was done outside, so maybe something in the air. The spots' appearance would seem to suggest something airborne, although at that point it seems like it comes down to bad luck. Really, I didn't think that Tamiya spray was quite that sensitive to contamination, maybe it is and I just haven't come across the discussion. Happens to me often enough that I almost expect it, just not two in a row and other projects get delayed. Really appreciate the advice!

[stitchdup]

48 minutes ago, DeanF said:

Hey, I really appreciate the replies, thank you! Lots to think about and I'm now re-thinking of everything that had contact with the body. I will say though I tend to agree that the gloves are probably less likely to be the source since yes, the body was handled all over with them and the spots are only on the roof. I actually masked off the exterior with a plastic bag and masking tape, so there are two more potential sources. In addition to that I used a tack rag kept in a sandwich bag immediately prior to spraying. I like the idea of wiping down with isopropyl alcohol or mineral spirits, what do you use to wipe it with that won't leave lint? I believe prep is the foundation for a successful paint job, so I'm still open to any suggestions. No air fresheners, and spray painting was done outside, so maybe something in the air. The spots' appearance would seem to suggest something airborne, although at that point it seems like it comes down to bad luck. Really, I didn't think that Tamiya spray was quite that sensitive to contamination, maybe it is and I just haven't come across the discussion. Happens to me often enough that I almost expect it, just not two in a row and other projects get delayed. Really appreciate the advice!

wipe it down before you tack it and lint wont be a problem. i use cheap kitchen towel or an old glasses cloth. you said you had 2 paint jobs in row where this happened so try a new tack rag as it will have contamination from the previous paints on it. If your spraying outside i would tend to think it could be cement dust contamination if there any construction nearby as theres al sorts of stuff that messes up paint in it. also, you if you wash it at the kitchen sink that could be the source of contamination. I tend to use the bathroom sink as it only has soap type products while the kitchen has all sorts of food oils 

[peteski]

3 hours ago, DeanF said:

I like the idea of wiping down with isopropyl alcohol or mineral spirits, what do you use to wipe it with that won't leave lint?

Blow the lint off using compressed air.  If you have a compressor make sure that oil/water trap is installed so the air is clean.  Or maybe use those "blow-off" aerosol duster cans.  If the lint is really stuck on, use one of those (again clean) makeup brushes while blowing the model clean.

[R. Thorne]

This is what I use.

[Bainford]

Those alcohol wipes look like a neat idea. 
I have recently picked up a microfibre cloth, the type used for cleaning eye glasses, but haven't tried it yet. After giving it a good cleaning I'm going to try it as a lint-free wipe with alcohol. 

[DeanF]

Really appreciate all these suggestions, everyone. Model has been stripped, but before I get try again, I think I'll try wiping with the alcohol on a test piece and see how that goes. I've got some of those little alcohol wipes as well. Great idea. A new tack rag is definitely in order as well. 

[bobss396]

I had used tack cloths made for the hobby for a very short while, I had fish-eyes as well. The tack cloths went right into the trash. I had a can of compressed air I was using to dust off models. Now I wash the bodies with soapy water rinse and give them 20 minutes in the dehydrator to dry. No dust.

[Dave G.]

I don't use tack cloths at all,never have. I use the OMS on tissues, then blow off with my airbrush using just air. Or canned air will work as has been mentioned. In 1/1 I found tack cloths to be more trouble than they're worth, sometimes picking up trash from one spot and putting it down elsewhere. Or if there is chemical contamination, if you think about it, it gets on the cloth. I tossed those things in my first year of 35+ years shooting 1/1. And never used them in nearly 60 years of painting models.

[DeanF]

40 minutes ago, Dave G. said:

I don't use tack cloths at all,never have. I use the OMS on tissues, then blow off with my airbrush using just air. Or canned air will work as has been mentioned. In 1/1 I found tack cloths to be more trouble than they're worth, sometimes picking up trash from one spot and putting it down elsewhere. Or if there is chemical contamination, if you think about it, it gets on the cloth. I tossed those things in my first year of 35+ years shooting 1/1. And never used them in nearly 60 years of painting models.

You know, I've have wondered about tack cloths themselves with the sticky wax I think it is, if they could be a problem, but I could see where they could actually spread contaminants. Thanks!

[Ace-Garageguy]

20 hours ago, Dave G. said:

In 1/1 I found tack cloths to be more trouble than they're worth, sometimes picking up trash from one spot and putting it down elsewhere. Or if there is chemical contamination, if you think about it, it gets on the cloth.

Agreed.