Paint crazing

[Lurch209]

I primed & painted my revell 54 Chevy sedan(1985 release). The primer and color coat laid down nicely on the body but not so on the hood or interior panels. 

When I sprayed the latter they wrinkled up or crazed. I assumed it was the paint but after having removed it in purple power it seems the plastic itself had a reaction to the paints. The actual plastic has the crazing lines in it. They were fine with the primer. It wasn’t till I sprayed the color coat that they wrinkled/crazed. 

Any one have this happen before or know why?

Primer coat on both was rustoleum black primer. Color coat on hood was rustoleum gloss black, color coat on seats was an old can of krylon tan. 
 

Edited May 17, 2022 by Lurch209

[Lurch209]

6 minutes ago, Lurch209 said:

I 

Edited May 17, 2022 by Lurch209

[Ace-Garageguy]

Most of us have had it happen at least once.

It's always caused by the material being sprayed being too "hot" for whatever the substrate is.

Some paints and primers have solvents that will attack plastic just like glue does...even some paints that are supposedly made for plastic.

The case for TESTING on the underside of whatever you're painting can not be overstated.

 

[Rocking Rodney Rat]

Ditch the Rustoleum. Go with Duplicolor DAP-1699 (find that SKU letter/number on the label near the bar code) primer. This is a light grey, sprays on smooth and sands well. Avoid the DAP-1700, a darker grey, it doesn't sand as well. Available at auto parts stores. I have NEVER had it mess up any plastics or resin. Don't put paint on too heavy. A few lights coats are better. Use Tamiya paints (yeah, they're expensive, but worth it). My $.02 and worth both pennies.... -RRR

Edited May 17, 2022 by Rocking Rodney Rat

[peteski]

Lurch, if I may suggest, maybe in the future do not use black text on dark gray background -- it is hard to read that way.  I'm not even sure how you did that  in the first place.

[StevenGuthmiller]

Yup, the paint was too hot for the plastic, and whatever primer was used was insufficient to protect it.

I agree with Rodney about ditching the Rustoleum paint.

There are far too many “good” paints on the market to risk the cheap stuff.

A good primer is a must with any lacquer, and more is better than too little when it comes to protecting the plastic.

Find a good lacquer primer, use several coats of it, and you should be able to spray almost anything over it without issue.

 

 

 

Steve

[Lurch209]

Thanks fellas, I think I will try a different paint like the ones suggested though I don’t think the paint/primer could of been to hot(80 degree day, paint stored in a room temp garage)either way I don’t think I’ll reuse the previously used stuff. 

Ill post some pics of it once I get it all resprayed though it may be a little while as it’s a two tone.✌🏽

ps my apologies on the darkened letters, I’m not to sure how I did that.

Edited May 17, 2022 by Lurch209

[Miatatom]

1 minute ago, Lurch209 said:

 I don’t think the paint/primer could of been to hot(80 degree day, paint stores in a room temp garage)either way I don’t think I’ll reuse the previously used stuff.

I don't believe they're talking about the actual temperature of the paint, they're talking about the chemical properties being too strong for the plastic and etching or "melting" the plastic.

[Plowboy]

Consider it a lesson learned on what happens when you use products not formulated for styrene. I used to do it and it's like banging your head against the wall. It feels so much better when you stop doing it! I now only use Tamiya primer and paint.    

[StevenGuthmiller]

Yes, as Tom said, it has nothing to do with the paint’s temperature.

”Hot paint” is a term used to describe a paint that has harsh chemicals that are not compatible with styrene plastic.

You can use these types of paint on plastic, but proper preparation is an absolute must to guard against damage.

 

 

 

Steve

[Miatatom]

26 minutes ago, Plowboy said:

 I used to do it and it's like banging your head against the wall. It feels so much better when you stop doing it! I now only use Tamiya primer and paint.    

😂 Been there, done that. I still experiment though. Rustoleum acrylic enamel clear works over stuff like Createx and some craft paints.

[Lurch209]

I see, lol at the banging head comment😂

[peteski]

Yes, "hot" paint or thinner in modeler's colloquial terms doesn't mean actual temperature of the liquid.  It means that the solvents in it are strong enough to attack (melt) polystyrene or ABS plastic the kits are made of.  This was not a problem back in the day when modelers assembling plastic kits only used hobby paints (Testors, Pactra) which were specifically formulated to be mild (or "cool") enough not to negatively affect the plastic surface. Those were plastic compatible paints.

But then modelers wanted to build model cars which had same color as the real cars, so they started using automotive touch-up paints designed for 1:1 metal-body cars.  Those paints are usually lacquers which use solvents that are strong enough to attack plastic.

Using a primer often creates a barrier for the solvent in hot paints not to attack plastic, but it is not a cut and dry process - you have to experiment to make sure the combination is safe to use.  Same with using multiple brands/types of primer/paint/clear.  There are some combination that will and some that won't work.

Safest bet is to use hobby paints designed for plastic models.  Many of the brands were discontinued, but one still going strong is Tamiya.  But they also make paints for polycarbonate RC car bodies, so be careful which line of Tamiya paints you choose. Some say that those paints are too expensive. Well, it is all relative.  If you don't want to worry about paint compatibility or crazing, then Tamiya is a pretty safe bet.

Edited May 18, 2022 by peteski

[Lurch209]

Peteski do you know which of the tamiya paints is for model kits? 

[peteski]

7 hours ago, Lurch209 said:

Peteski do you know which of the tamiya paints is for model kits? 

Yes, in spray cans, the TS (Tamiya Spray) are the ones with glossy car paints.  Those are plastic compatible.

The AS (Aircraft Spray) are also plastic compatible, but are flat finish, and the colors selection is what you would finish on military aircraft (camo). Many colors are good for car interior  colors. Basically, it is the same chemistry as TS line, but different color range.  I guess they created separate line for more merchandising.

The PS (Polycarbonate Spray) line is the one which might be too "hot" for painting polystyrene kits.  Those are designed to paint the clear polycarbonate body shells of RC cars (from the inside).

The other Tamiya paints (in jars) should all be safe on polystyrene.

Here is the website: https://www.tamiyausa.com/shop/paints/  you can select the specific paint lines in the left column

Edited May 18, 2022 by peteski

[Lurch209]

thanks peteski. I always forget which are which with tamiya. I’m going to hobby town hopefully tomorrow to pick some up. 

[Lurch209]

First time using tamiya primer. This stuff sure does spray pretty nice, looks to be superior to rustoleum for sure! I’ll probably continue using it in the future though I’m not crazy about the price. Here’s a picture I took after spraying with it. 

[showrods]

25 minutes ago, Lurch209 said:

First time using tamiya primer. This stuff sure does spray pretty nice, looks to be superior to rustoleum for sure! I’ll probably continue using it in the future though I’m not crazy about the price. Here’s a picture I took after spraying with it. 

I would add to what peteski said - if you're using Tamiya bottles...paints coded starting with XF are flat and those coded starting with X are gloss.  e.g XF-42 is flat; and X-19 is gloss.

Edited May 18, 2022 by showrods

[Dpate]

Ditch the furniture paint and use quality products.  Tamiya primer in the can, Mr.hobby primer in the can and even ammo by migs primer is AMAZING.  Self levels beautifully, sands great if needed, very nice matt finish.  Makes your parts look like they were actually molded in the color lol.  I only listed raddle cans because I'm assuming you don't have a airbrush?

Edited May 18, 2022 by Dpate

[peteski]

5 hours ago, Lurch209 said:

First time using tamiya primer. This stuff sure does spray pretty nice, looks to be superior to rustoleum for sure! I’ll probably continue using it in the future though I’m not crazy about the price.

Yes, it is more expensive than the hardware-store paints, but well worth it.  It is quality stuff.   Model building is your hobby - splurge on good paint.  It's not like you need gallons of the stuff to paint a small model.

[Ace-Garageguy]

6 hours ago, Lurch209 said:

First time using tamiya primer. This stuff sure does spray pretty nice...

Yup, first time I broke down and used Tamiya primer, I felt like an idiot for holding out so long. Sprays sweeeeeeet.

And the cost is well worth it to me, knowing I won't have any weird crazing to deal with in the future; I have several relatively expensive and rare models that I had one hello of a time saving after they crazed with hot automotive primer that I'd been getting away with using for years.

[Lurch209]

2 hours ago, Dpate said:

Ditch the furniture paint and use quality products.  Tamiya primer in the can, Mr.hobby primer in the can and even ammo by migs primer is AMAZING.  Self levels beautifully, sands great if needed, very nice matt finish.  Makes your parts look like they were actually molded in the color lol.  I only listed raddle cans because I'm assuming you don't have a airbrush?

Thanks for listing those brands. I actually do have an airbrush that I picked up at Harbor freight, a little cheapie one. I have not used it yet because I’m unfamiliar with airbrush. Mainly the only thing holding me back is not knowing how and when to mix or rather dilute paints. I hope to mess with it soon. 

Edited May 19, 2022 by Lurch209

[Miatatom]

One thing I'd like to add to this discussion is Tamiya primer is really hard to remove, if you need to. IPA will remove most paints but Tamiya primers are like granite. I haven't found anything that will completely remove it easily.

[StevenGuthmiller]

41 minutes ago, Miatatom said:

One thing I'd like to add to this discussion is Tamiya primer is really hard to remove, if you need to. IPA will remove most paints but Tamiya primers are like granite. I haven't found anything that will completely remove it easily.

True.

most of the time, when I hear someone complain that Super Clean won’t remove lacquer paint, it’s due to the fact that they used a primer such as Tamiya.

It’s a pretty simple operation to remove lacquer depending on the primer.

A primer such as Duplicolor or Testors will dissolve and the lacquer will slough off in sheets.

So in short, keep in mind that if you do plan on using Tamiya primer, you’re going to have limitations as to what you can use to remove it, and any lacquers that you might use over it, should the need arise.

 

 

 

 

Steve

Edited May 19, 2022 by StevenGuthmiller

[StevenGuthmiller]

1 hour ago, Lurch209 said:

Thanks for listing those brands. I actually do have an airbrush that I picked up at Harbor freight, a little cheapie one. I have not used it yet because I’m unfamiliar with airbrush. Mainly the only thing holding me back is not knowing how and when to mix or rather dilute paints. I hope to mess with it soon. 

There are a whole host of really great pre-thinned paints available that will require no mixing or thinning whatsoever.

shake ‘em up, pour in the cup or jar and go to work.

MCW and Scale Finishes, (just to name a couple) will carry just about any color that you can imagine!

They are an invaluable resource for paint, especially if you are looking for particular factory stock colors.

Whatever color it is, between the two of them, they’re almost guaranteed to have it.

 

 

 

Steve