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Issue with Zero paints on Gunze Sangyo kit


timo944
05-16-2020, 06:49 PM
Hi All - I discovered this forum while browsing for answers to my problem. I guess I've been lucky enough =not to have issues in the past, but anyway really happy to finds a place where I can get help and maybe provide some advice.

I recently started a kit from the closet - a Ferrari 250 SWB. Wanting to build the car that my Dad's hero Stirling Moss drove, I procured some Zero paints Rob Walker blue lacquer and their grey primer and gloss coat. I used the primer on another kit (Tamiya) and it worked great, even with a top coat of Tamiya spray cans. I'd had some concerns about paint compatibility but this turned out to be an issue.

When building this Gunze kit however, I have found something I have never encountered before. The primer seemed to be OK, except that the surface of the paint would get quite rough. I had to prime a few times, and finally, after some sanding and smoothing I was convinced that I had a good primed body ready to go. My plan was several light mist color coats, then a couple of medium coats to ensure that I had good depth of color. I used 30psi and my Paasche single action airbrush, Mixed the paint really well. No thinning, paint seemed to flow really well.

After about 4 light mists, things were looking OK, except that I had a rather dull surface, and the color was not so deep (as expected). I increased the flow a bit, and started to put some medium coats. I did not leave much time between the mist coats and medium coat, maybe 2-3 minutes.

After the first coat, there was enough shine to the paint that I figured I was applying the right amount. Waited another minute or two and then applied a 2nd medium coat. The paint was going down wet on the surface but the I started to see orange peel. I panicked and stopped painting. I noticed that the peel was getting much worse. It was a strange peel as if the air brush had pushed it around,

After drying I started to check in to it. A light sanding on the roof showed right away that I went through the blue and into the primer at the tops of the ridges of the peel. I decided a full strip and respray was needed, and a different strategy. I cleaned off the paint with brake fluid, and to my horror, the orange peel is actually etched into the surface of the plastic. I suppose that with a lot of careful sanding it will be recoverable.

Thinking about it now, it seems to me that the primer might have been doing the same thing. It certainly behaved differently than on the Tamiya model. By using light coats I was able to stay out of trouble.

What happened? Did I get to aggressive with the paint? Or is this simply incompatibility between paint and plastic?

And what to do now? I saw some posts about using Tamiya primer, but not sure that this will solve the issue because it's still lacquer and might cause the same issue. And I don't have any other plastic from the kit to test either.

My thinking is:
a) fix the body
b) prime again with the Zero paints primer, using very light coats, as much as I have left in the bottle. Maybe allow a long drying time between each coat
c) paint again, in the same manner as the primer, just light coats, until I get the depth of color needed
d) and same with the clear coat. I may need to do some polishing to get a good shine but I'm OK with that.

Plan B: Paint eh car red with Testors enamel

Any ideas?

Tim

360spider
05-16-2020, 08:20 PM
Tim,
Zero paints are all base colors, meaning they are not supposed to be glossy. They all require a clearcoat.
Zero paints are also what we call "hot paints" - solvents will melt the plastic if sprayed directly without primer. You seem to have that covered, so the only reason I think you got the orange peel is spraying too much paint without letting the previous coat flash - 2-3 minutes is not nearly enough.
I'd strip the paint and primer, and start again. Easier that way.
To strip, just find a suitable plastic container and fully submerge the body into 91% isopropyl alcohol for a couple of days. Have to be 91% or higher. Paint should come off with some brushing and you will be good to try again.

timo944
05-17-2020, 06:21 PM
Thanks for the reply. I have removed the paint and the body is badly pitted. I've sanded as much as I can and it's going to need some filler.

Anyway - for the rest between coats - is 20 minutes about right?

Thx

ulap1
05-17-2020, 07:04 PM
Scalemodeling channel on Youtube offers many videos of builds using Zero paints. If I remeber correctly the intervals are 5-20 minutes, it depends whether you use top color or gloss coat.
Several members of our local model forum had similar issues with Zero paints being too hot and attacking plastic, causing wrinkles on surface of a model. They suggest to use Gunze Leveling thinner to avoid such situation. Just add 3-4 drops of it into airbrush cup filed with Zero paint. This method may solve your problem, too.

360spider
05-17-2020, 11:27 PM
Thanks for the reply. I have removed the paint and the body is badly pitted...

Thx

That means the primer failed, and paint attacked the plastic. What brand primer did you use? Zero?

I'd flash at least 10 min before applying another heavy paint coat.

timo944
05-18-2020, 10:37 AM
[QUOTE=360spider;7222764]That means the primer failed, and paint attacked the plastic. What brand primer did you use? Zero?

The primer is Zero Paints Grey (ZP-3032).

timo944
05-18-2020, 10:39 AM
Scalemodeling channel on Youtube offers many videos of builds using Zero paints. If I remeber correctly the intervals are 5-20 minutes, it depends whether you use top color or gloss coat.
Several members of our local model forum had similar issues with Zero paints being too hot and attacking plastic, causing wrinkles on surface of a model. They suggest to use Gunze Leveling thinner to avoid such situation. Just add 3-4 drops of it into airbrush cup filed with Zero paint. This method may solve your problem, too.


Something strange is that the primer seemed to attack the plastic too. For example, I had completely sanded out the mold lines, but when priming it seemed that they would reappear a bit, almost as if they opened up, and I had to re-sand and re-prime. I learned to make several light coats not to bring the lines back out.

I watched the videos and I am applying a lot less paint, especially at the beginning. As said above, the primer coat was several light mists.

BUT - I had no problems like this on Tamiya plastic! I think the Gunze plastic is somehow softer that Tamiya

SO - I will try to source some of this leveling thinner from Gunze and see if that helps. It looks like it might be hard to find.

Thanks

stevenoble
05-19-2020, 05:38 PM
I've had plenty success with Zero paints, but the Zero primer is horrible stuff and I just can't get on with it at all. I use Tamiya Fine Surface primer instead and it's perfect. Apply the Zero paints colours lightly, no need for wet coats. I allow around 5 mins between coats only. Build up the colour over several light coats. You will not get any shine from Zero paints, they dry matt/semi matt. The clear will give you shine and gloss. You can clear after 30 mins should you desire, but I wait for around an hour or overnight with metallic shades.

timo944
05-19-2020, 09:22 PM
I've had plenty success with Zero paints, but the Zero primer is horrible stuff and I just can't get on with it at all. I use Tamiya Fine Surface primer instead and it's perfect. Apply the Zero paints colours lightly, no need for wet coats. I allow around 5 mins between coats only. Build up the colour over several light coats. You will not get any shine from Zero paints, they dry matt/semi matt. The clear will give you shine and gloss. You can clear after 30 mins should you desire, but I wait for around an hour or overnight with metallic shades.

Thanks Steve. I ordered the Zero Paints primer with the paint. It's more or less empty now, so i'll try the Tamiya. I see that it's lacquer so it should not react. Of course I will test first

stevenoble
05-20-2020, 09:47 AM
Thanks Steve. I ordered the Zero Paints primer with the paint. It's more or less empty now, so i'll try the Tamiya. I see that it's lacquer so it should not react. Of course I will test first

Yes the Tamiya primer is lacquer based and is suitable under Zero paints. I've used it for many years under all types of Zero paint and never had any problems whatsoever.

timo944
05-20-2020, 10:33 AM
Yes the Tamiya primer is lacquer based and is suitable under Zero paints. I've used it for many years under all types of Zero paint and never had any problems whatsoever.

I always get thrown by the description of Acrylic. Itís not always obvious that itís a lacquer. I always get thrown by the spelling of lacquer too but thatís another story.

Iíve done a lot of filling and sanding. The body is a mixture of plastic white, grey primer speckled by squadron green and still needs some work, but I think it will be ok. When I get the primer I will move forward and then paint as you have all suggested. I hope to post a picture of the finished product in the next week or two!

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