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Scale Finishes - Blotchy Paint


25 posts in this topic

Posted

So I'm  having another interesting problem with Scale Finishes paint.  I am not sure it is specific to that brand.  Here is the story.

First, spoons.  I very often test paint on plastic spoons.  I bought a box of 1000 styrene spoons and have bene using them for years.  Lately, the spoons show a glossy/not glossy pattern on them - see the photo below.  This is with MANY different brands of paint, so I assume it is something to do with contamination in the plastic of the spoon.

I tested the Dark Camel color from Scale Finishes on a spoon, and it exhibited the problem.  After I applied the paint to the car, I noticed the same problem.  See the photos - there are non-glossy patches on the body.  This is after several light/medium coats of the paint, and it looked fantastic wet.  As it dried, it got blotchy.

Notice the picture of the hood, though - it looks great.  Yeah it's orange-peely but this is before any gloscoat or sanding/polishing.

--> What is going on with this blotchy paint!?  Does anyone have any insight?

Hoping that gloss coat would make it look right, I took my test soon and put on TWO medium/heavy coats of alclad clear kote, then a very heavy coat.  When wet it looked like glass, but after it dried - blotchy.  So it seems that no amount of clear coat is going to fix this.

It is possible that the hood has more primer on it than the body.  I had to fill dimples and depressions, and to cover the putty and sanding it took more primer.  Is that the key?  A lot more primer?

Any help you all can give would be great.  Thanks.

 

Bad Body Paint 1.jpg

Bad Body Paint 2.jpg

Bad Body Paint 3.jpg

Bad Body Paint 4.jpg

Bad Spoon 2.jpg

Good Hood Paint.jpg

Monte Carlo Box.jpg

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Posted

In a word, humidity.

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Posted

Thanks 935K3.  Humidity is unlikely I think, though.  I paint in my basement and humidity is fairly constant there.  And the spoons exhibit the same pattern, many days apart.  I've done a fair amount of woodworking and understand blushing in lacquer finishes.  This isn't blushing.

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Posted

Is this being sprayed directly on the plastic or you spraying it over primer?? I am wondering if your first coat is a little too heavy and the solvents could possibly be a little too Hot for the plastic and it's crazing the plastic just a little bit. I have had crazing issued on my models before and I tend to mist a few first coats and then I can a little heavier coat after that. Also is it just the Scale Finishes paint your are seeing this on or is it also different brands of model paint?

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Posted (edited)

What are you using to thin your paint? Both the roof of the model and the spoon appear to have solvent crazing.

A thinner or solvent that's too "hot" will attack the surface of the plastic, causing paint to go dull and "blotchy" as the solvents evaporate out during drying.

The fact that you primered the hood more, and the problem isn't as severe, would be consistent with that. The additional primer blocks the solvent from getting to the plastic...but burying the model in primer isn't the solution, as it obliterates fine details.

In general, the plastic that models are made from has been cheapened recently, and solvent resistance is poor. Many of us have noticed this, and it has been discussed at length.

I would also respectfully recommend two things.

1) Practice your spray technique until you don't get orange peel. It's not necessary, and burying it in clear isn't really the right way to deal with it.

2) Make 100% certain of your materials and techniques BEFORE painting a model you care about.

Another word of advice: spoons may NOT be the same plastic that models are made from these days, and what works on a spoon, though it's widely recommended by "experts", may very well NOT WORK THE SAME ON A MODEL.

Once you get your technique perfected, your paint should look like this with NO clear or polishing.

Image result for ace-garageguy 50 olds

 

Edited by Ace-Garageguy

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Posted (edited)

Is this being sprayed directly on the plastic or you spraying it over primer?? I am wondering if your first coat is a little too heavy and the solvents could possibly be a little too Hot for the plastic and it's crazing the plastic just a little bit. I have had crazing issued on my models before and I tend to mist a few first coats and then I can a little heavier coat after that. Also is it just the Scale Finishes paint your are seeing this on or is it also different brands of model paint?

This is what it looks like to me.

Basically, you could call it crazing.

The paint is being sprayed too heavily & the solvents are eating through to the plastic.

I'm assuming that Scale Finishes paint is the same as MCW paints, which are automotive lacquers.

Far too hot to be sprayed over bare plastic.

Even with priming you need to be careful.

Use plenty of primer & spray several light coats of color.

I use as many as 5 or 6 coats of primer.

Save your wet coat until the end.

Even then, don't expect a shiny finish with an automotive lacquer.

They are designed as a 2 part system.

Color, followed by clear coats.

 

Steve

Edited by StevenGuthmiller

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Posted

Even then, don't expect a shiny finish with an automotive lacquer.

They are designed as a 2 part system.

Color, followed by clear coat

I agree with MOST of what Steve says, however, having been painting REAL cars with automotive lacquer for over 40 years, I have to say that the true "automotive lacquers" are NOT intended to be primarily 2-part systems. The basecoat-clears most painters are familiar with today are urethanes, not "lacquers".

That said, many METALLIC lacquer colors don't like to be color-sanded and polished, and will definitely benefit from a clear topcoat prior to polishing...IF they're sprayed clean with minimum orange peel.

SOLID "lacquer" colors don't need a clear topcoat. They can be sanded and polished to a high gloss with no adverse effects.

Part of the idea is to get as LITTLE paint material on the modea as possible and still get the gloss you want. This avoids the "dipped in syrup" look.

You must also be wary of how you shoot multiple "light coats" of paint. Done wrong this is a recipe for horrible orange-peel. Practice and experimentation is the ONLY way to develop your skills and painting technique.

Steve Guthmiller's work is exceptional and consistently beautiful, and you can do well by heeding his advice.

I only made the above comments to eliminate the possibility of confusion about terminology.

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Posted

agree with all of the comments and possibilities above - it could be any of these things or a combination

plus bonus one more possibility - there may be contamination or moisture in the air supply - (it's happening on multiple projects so that's kind of a clue) - drain the tank, check the filter and maybe add something to take moisture out of the air.  Basements are tricky because they can pickup moisture thru the walls from the ground.

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Posted

I agree with MOST of what Steve says, however, having been painting REAL cars with automotive lacquer for over 40 years, I have to say that the true "automotive lacquers" are NOT intended to be primarily 2-part systems. The basecoat-clears most painters are familiar with today are urethanes, not "lacquers".

That said, many METALLIC lacquer colors don't like to be color-sanded and polished, and will definitely benefit from a clear topcoat prior to polishing...IF they're sprayed clean with minimum orange peel.

SOLID "lacquer" colors don't need a clear topcoat. They can be sanded and polished to a high gloss with no adverse effects.

Part of the idea is to get as LITTLE paint material on the modea as possible and still get the gloss you want. This avoids the "dipped in syrup" look.

You must also be wary of how you shoot multiple "light coats" of paint. Done wrong this is a recipe for horrible orange-peel. Practice and experimentation is the ONLY way to develop your skills and painting technique.

Steve Guthmiller's work is exceptional and consistently beautiful, and you can do well by heeding his advice.

I only made the above comments to eliminate the possibility of confusion about terminology.

You're correct Bill, I'm not all that familiar with the correct terms for types of paints.

For the sake of discussion & to keep things less confusing, (at least in my mind) I refer to pretty much any automotive type paint, such as Scale Finishes, MCW, Duplicolor, etc, that the average builder will use, as lacquer.

Likewise, I consider Testors lacquer & Tamiya paints as lacquer as well.

I'm no chemical engineer, so the technical terms for the makeup of these paints escapes me.

I'm thinking more of the properties of the paint.

My world basically consists of either lacquer, enamel or acrylic. :)

That's pretty much where my knowledge ends.

That being said, any "hot" paint is going to give you trouble on styrene without proper preparation, & while not necessary in all cases, most of these "lacquers" will benefit from clear coats, especially metallic colors.

 

Steve

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Posted

Thanks everyone.  The consensus is that it is crazing, and that lines up with what I'm seeing here.  

Further info:

Primer - the car body was primer'd with Tamiya white primer.  The hood and trunk had more primer, as they had been filled/sanded and the body had not.  I think they had enough primer to prevent the crazing problem.  I do not usually primer the test spoons, so the paint usually goes right onto the plastic.

Test spoons - The problems actually show up on only A FEW brands, not all.  The shot below shows three spoons with the problem - those brands are Rustoleum Satin Black, Scale Finishes Dark Camel, and Quick Color black (this one actually bubbled after I sprayed it).  The top two are Model Master "wood" color enamel jar paint, thinned with MM enamel thinner for the airbrush; and Model Master spray can Hemi Orange.  All of these spoons were sprayed recently, but the top two don't have any problems.  My bucket of spoons, all from the same box of styrene spoons (I researched spoons and got styrene, the same thing models are made of), and I never had this problem until I started branching out from Testors/Tamiya paints.

Humidity - my basement is pretty much a constant 63% humidity.  Not low, but not too high.  I use 65% as the threshold above which spraying starts to become risky.  

So, it seems that some brands of paint are hotter than the others, and have more of a crazing problem.  

What I plan to do is:   strip the car body, re primer with enough to seal the plastic well, reshoot with Scale Finishes Dark Camel.

--> Does anyone know of a better way to "seal" the plastic, other than multiple coats of Tamiya primer?

Bad Spoons, Good Spoons.jpg

All Spoons.jpg

Humidity 63.jpg

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Posted

I have had similar problems when I tried using some of the new paints like Scale Finishes and Gravity Colors. Part of it was using an airbrush which couldn't flow enough paint, but I also found that I would get blotches on areas where the color coat ate through the primer. I use Plasti-Kote T-235 as my primer, but there were some areas which were not protected well.

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Posted

I have had the same problem with automotive paint and Tamiya primer. Now whenever I use automotive paint, I prime with Duplicolor primer from the auto parts store.

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Posted (edited)

This has happened to me a couple of times using Scale Finishes, and I thought it was because I unknowingly got a little carried away with too heavy of coats and not letting the coats dry sufficiently in between each other. Easily fixed with a little sanding and very light respray coats.

Edited by BVC500

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Posted (edited)

--> Does anyone know of a better way to "seal" the plastic, other than multiple coats of Tamiya primer?

 

Technically, I don't think that I would call this crazing, but regardless of what you call it, it looks to me like it was caused by insufficient priming/sealing, & the paint burned through the primer to the plastic.

I have had similar issues & I believe it was probably a combination of factors that caused it.

First, there was probably not enough primer, and, or too heavy of a color coat.

These types of paints adhere by dissolving the layer beneath it to bite into it.

If there is not enough primer or paint between it & the plastic, you'll get this type of phenomena.

Secondly, compatibility between the primer & paint is a factor as well.

I decided, when I had this issue, that the cause was most likely a reaction between the Testors lacquer primer I was using at the time & the MCW paint.

It almost looked like the paint was dissolving the primer & raising it to the surface.

You could see a faint gray hue to the areas where the splotches were, almost like the primer was showing through.

 

Anyway, a good "primer sealer" should help for sealing things up as well.

I've started using Duplicolor primer sealer & it seems to help with any of these "crazing" issues.

You might want to try a different primer as well.

Automotive paint is formulated differently than most model paints & as we all know, compatibility between different paints can be an issue.

Just be aware that some automotive primers can be pretty hot as well, so light coats are the key.

 

Steve 

 

Edited by StevenGuthmiller

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Posted (edited)

 

...I researched spoons and got styrene, the same thing models are made of), and I never had this problem until I started branching out from Testors/Tamiya paints.

 

Seems like a reasonable conclusion, but unfortunately, you are not in possession of ALL the information.

"Styrene", or more correctly "polystyrene", is available in literally countless formulations. Some are harder and more brittle and more chemical resistant, and some are softer and more pliable and much less solvent resistant.

I have some Johan models from the early 1960s that are entirely resistant to the HOTTEST real-car paint products on the market. Rattlecan SEM-brand self-etching primer won't TOUCH the surface of these things, and can be shot wet enough to flow out slick. The shot below is HOT HOT HOT SEM black self-etching primer on a 1961 Johan model. Look closely at how smooth the black is.

Image result for ace-garageguy project phoenix

But shoot that stuff "wet" like that on a current-production Chinese model car body, also made of "styrene", and the surface WILL wrinkle like you hit it with a torch. The crazing WILL be so bad that the model is only suitable for the rusty rat-rod treatment, or the trash.

Mr. Guthmiller builds a lot of early Johan and AMT-based models, presumably made of the much higher-quality "styrene" from years past, so he may not be experiencing the full impact of the problem with poor solvent-resistance of the recent bottom-of-the-barrel "styrene" formulations most manufacturers are pushing on us these days.

And rather than using higher quality materials and instituting some kind of minimum quality standards for kits, SOME MANUFACTURERS ARE NOW RECOMMENDING THAT YOU PAINT THEIR MODELS WITH WATER-BASED ACRYLICS ONLY.

What you're experiencing IS INDEED CRAZING, no doubt about it...and one reason I haven't been building much lately is that I got so disgusted by the poor solvent-resistance of recent kits that I put a moratorium on building until I worked out a foolproof system of prep and paint, one that works as well and as predictably on the new CRAPP "styrene" we're getting, as my old time-proven materials and techniques worked on the older, harder plastics.

Bill Geary (MrObsessive) has had some success using a specific hardware-store sealer as a barrier to combat this problem. Hopefully he will chime in here.

Here is a thread I started some time back that discussesthe issue in some depth...

 

 

Edited by Ace-Garageguy

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Posted

For sealer, Zinsser-Bin may be a good option.

Ah yes...that's the one MrObsessive has recommended too, and his work is also among the best, making his advice worth listening to.

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Posted

Bill is right, I do build a lot of older kits.

But I've built plenty of newer ones using the method that I use now with good results.

It took me quite a while to come up with a system that works for me & a lot of guys probably won't like it, but it's been giving me restful nights.

I use a "LOT" of paint, including primer, but if it's done correctly, you won't get that "dipped" look or any hide of detail.

Here's how I do it.

One or two coats of Testors lacquer primer, gray or white. ( I find that it covers better than many other primers)

As many as 4 or 5 light coats of Duplicolor sandable primer. (any color) I've also begun using the primer sealer in the same fashion, mostly because the color is a lighter gray than Duplicolor sandable gray primer.

I start light & work my way to successively heavier coats with that primer as well as the color coats. About 3 or 4 coats of color as well.

Then I follow it up with anywhere between 3 to 5 coats of clear.

I use mostly Duplicolor clear in a rattle can.

So, as I said, a lot more paint than most guys care to use, but when it works for you, why change it.

These Chevies were all done using this method with MCW paints.

All new tool kits.

 

Steve

 

'55 Belair 5DSCN2987'58 resize

 

 

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Posted

Steve...are you decanting / thinning and airbrushing most of your materials? If not, how do you manage to not fill all the details with primer / paint?

Whatever you do, the results are always stunning...especially for 1/25 scale.

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Posted

Steve...are you decanting / thinning and airbrushing most of your materials? If not, how do you manage to not fill all the details with primer / paint?

Whatever you do, the results are always stunning...especially for 1/25 scale.

No.

All of my primer & clear coats are shot straight from the can.

The Duplicolor primer & clear dries very thin.

You could never get away with this many coats with Testors paints, especially the clear.

You would be pretty much maxed out at 2 or 3 coats.

I think a big part of it is the spray nozzles.

The Duplicolor "fan spray" nozzles make a big difference.

Usually I will notice that the Testors primer dries thicker & will many times end up with a little bit of orange peel.

Several coats of Duplicolor primer will level that off nicely.

By the time I get to the 4th or 5th coat of clear I can begin to see a tiny bit of buildup developing around trim pieces, etc, but by then I'm done.

The small scripts get foil before the final color coat, so I never have problems with those.

I like to get a good base of primer to prevent any possibility of crazing or related issues, & nice amount of clear guards against any "burn through" problems during polishing.

These have been my 2 biggest issues since starting to use lacquer.

Now my biggest problem is getting a good even color coat.

Hopefully the new airbrush will remedy that.

 

As an example, scripts don't get much finer than the ones on the rear quarters & trunk lid of the AMT '59 Bonneville.

After a half dozen coats of primer & a couple of color coats, I was still able to get a good foil finish on them.

 

Steve

 

DSCN4040

 

The "300H" & "Chrysler" scripts on the back of the Johan '62 Chrysler were no better, & this one was painted entirely with Duplicolor rattle cans.

Probably as many as 12-14 coats total.

 

DSCN5807

 

 

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Posted

StevenGuthmiller - you said you put foil on before the last "color"coat?  Do you put a rectangle of foil, then color over it, then rub off the color on the script?  Then clear?  What is your technique for the script foiling?

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Posted

StevenGuthmiller - you said you put foil on before the last "color"coat?  Do you put a rectangle of foil, then color over it, then rub off the color on the script?  Then clear?  What is your technique for the script foiling?

That's pretty much it. :)

Only, don't put a "rectangle" of foil over the script.

Most times you will be able to see that rectangle under the paint.

The edges may show through slightly & the color may differ.

Your best bet is to cut your foil as close to the script as possible.

Other than that, you got it!

 

Steve

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Posted

Thanks everyone.  The consensus is that it is crazing, and that lines up with what I'm seeing here.  

Further info:

Primer - the car body was primer'd with Tamiya white primer.  The hood and trunk had more primer, as they had been filled/sanded and the body had not.  I think they had enough primer to prevent the crazing problem.  I do not usually primer the test spoons, so the paint usually goes right onto the plastic.

Test spoons - The problems actually show up on only A FEW brands, not all.  The shot below shows three spoons with the problem - those brands are Rustoleum Satin Black, Scale Finishes Dark Camel, and Quick Color black (this one actually bubbled after I sprayed it).  The top two are Model Master "wood" color enamel jar paint, thinned with MM enamel thinner for the airbrush; and Model Master spray can Hemi Orange.  All of these spoons were sprayed recently, but the top two don't have any problems.  My bucket of spoons, all from the same box of styrene spoons (I researched spoons and got styrene, the same thing models are made of), and I never had this problem until I started branching out from Testors/Tamiya paints.

Humidity - my basement is pretty much a constant 63% humidity.  Not low, but not too high.  I use 65% as the threshold above which spraying starts to become risky.  

So, it seems that some brands of paint are hotter than the others, and have more of a crazing problem.  

What I plan to do is:   strip the car body, re primer with enough to seal the plastic well, reshoot with Scale Finishes Dark Camel.

--> Does anyone know of a better way to "seal" the plastic, other than multiple coats of Tamiya primer?

Bad Spoons, Good Spoons.jpg

All Spoons.jpg

Humidity 63.jpg

I find if you are using automotive lacquers(Duplicolor/Perfect Match etc) Tamiya primer is not good enough..You need a thicker primer like Duplicolor or Plasticote sandable primers..And possibly two coats then lightly sanded for adhesion of the top coat..Just my experience..

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Posted

In the end the Monte Carlo came out ok.  After stripping it all back, I redid the finish.  The layers are:  Tamiya primer, Zissner-Bin, color coats (scale model finishes Dark Camel), Alclad clear coats, micro gloss polishing compound, "the treatment" model wax.  The primer/color/clear were pretty heavy coats, with sanding in between to even it out.  The Zissner especially needed flattening - it was beyond orange peel, it was "lumpy".  In the end the finish came out very nice. It is very brittle, though.  The slightest contact tends to chip the paint.  Does anyone know if Scale Model Finishes is usually this delicate?  I'm dissuaded from using them again.  Below are pics from done/nearly done.  

Done 1.jpg

Done 2.jpg

Nearly Done 2.jpg

Nearly Done.jpg

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Posted

I think the chipping is due to the layers under the color coat. I have never had an issue with Scale Finishes, it lays down smooth and very durable when it dries. 

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