Paint Cracking Problem

[Saj]

Hi, guys I have only been modelling for a few months and I am on my third build. I was hoping to get some advice on painting techniques. I seem to have a recurring problem of the paint cracking on my builds after I have applied the top lacquer layer. I am using auto spray paints from a can, specifically mean machine auto spray paint and mean machine clear lacquer spray which I bought from ebay. I think that maybe the top lacquer coat is reacting with the base coat to cause this but I am not sure. I was wondering how to achieve a nice gloss finish on my builds using spray paint as I don't want to invest in a airbrush kit just yet. Any help would be appreciated guys as it's very disheartening when the paint cracks after you've spent so much time and effort on the build. Thanks in advance, Saj

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[Ian M]

As you are using automotive rattle-cans, I will have to pass but I know we have a couple of real car sprayers here on the forum and I am sure that when they see your problem they will come with some solid advice. As you say that the paint and the clear are both the same system, the only thing I can think of is either the environment, or the time between the two coats.

I know that if you spray too much in one go and dry it to quick, it will have an effect like that. Also do you clean the base coat before you spray the clear.

If you can provide as much info as possible on how you work: surface prep, primers, first coat, top coat etc. I am sure some one will put you right.

Ian M

 

[andyrobs]

Hi Saj, a few tips that may help, some may not agree, but I've found they work. Give the surfaces a rub down with some very fine wet and dry to give the surfaces a key. Ensure all surface are clean, and grease ect free.Try using something to warm the surfaces before spraying, the paint dries quicker on the warm surfaces. Not enough heat can ceate the "orange peel"cracking effect. Don't try to put to much paint on in one go. Build up with lighter mist coats to get the coverage, especially with the laquer. May sure the base coat is dry and cured before appying the laquer. Try not to spray in a damp atmosphere.

Hope these help,

Cheers, Andrew

 

[dubster72]

A couple of points I can think of Saj. Firstly is that the automotive paint works much better with plenty of time for each layer to cure, rather than just dry. That prevents any adverse reaction between the coats.

Also, I appreciate you're saying you don't want to get an airbrush yet, but considering the cost of rattlecans & their lack of control, perhaps £70 for a budget airbrush & compressor setup would save a lot of frustration?

I've airbrushed automotive paint with good effects on small defects on my own car.

Cheers

Patrick

 

[CDW]

It just looks to me as though the paints been sprayed on heavily in one coat (almost to the point of running and filling up the fine detail ... i.e. on the red car bonnet and roof), then not had enough time to cure before the laquers been put on.

Its a little disheartening when you've got a nice model built and this happens, I have a couple of old helicopters stuffed in a box somewhere, from my first time modeling many years ago, that look the same so you're not on your own Saj

I think the paint will come off with household bleach, unfortunately i'm sure it takes the chrome off too .... i'm sure thats right ... someone will correct me if not.

 

[Ian M]

I think the paint will come off with household bleach, unfortunately i'm sure it takes the chrome off too .... i'm sure thats right ... someone will correct me if not.

I think the bleach trick is for hobby acrylic's I don't think it will touch auto lacquer. It will get the chrome off though. As will Break fluid.

Ian M

 

[yak face]

Hi saj , as the others have said , it looks as if you need a lot more drying time between the base coat and the clear laquer . Ive used quite a few different auto sprays straight from the tin , and have found that if used carefully , in not too thick coats with loads of drying time , they can give great results . Hope this helps , cheers tony

 

[Saj]

Hi, thanks for all the input guys. Just to go over my technique, I haven't cleaned anything before applying 2 coats of primer, followed by 2 coats of base paint and then two coats of lacquer. The drying time between each coat is probably a 6-7 hours or until touch dry. Listening to your comments it sounds like a combination of not cleaning and prepping the surface followed by too heavy coats of paint and then not allowing enough time for the paint to cure in between each layer. Regarding the airbrush kit it's not so much the cost rather i'm reluctant to venture into that territory as it seems a bit complicated for me yet i.e. thinning paints and cleaning the set properly after use etc. I think what I will do is strip down my first model which was a disaster and the paint it following all your advice and see what the outcome is. Just for reference what is the usual drying time between each coat of paint? I really want to get this sorted as I have a Revell 2010 Camaro kit which i'm eager to get started on. Once again I really appreciate all your advice, you guys have been great and i'll keep you posted on my results, Saj

 

[yak face]

Hi saj , sounds like youre on the right track.Personally I would give the kit a wash in soapy water (washing up liquid and luke warm water) then when fully dried a single thin coat of primer . The base coat would go on a day later ,again nice and thin coats, i dont do any sanding in between coats if its not absolutely necessary ,if another coat of the base colour is required then 24 hours before this goes on ,then another 24 hours before the clear topcoat etc. Either way up its a day in between coats of whatever paint youre using and nice thin coats . Ive found the halfords acrylic aerosols to be great , nice fine spray and good coverage , also Hycote acrylics are great too ,heres a pic of the finish you can get with them on my Caudron 460 cheers tony

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[Saj]

Wow that's an amazing finish. I'm gonna give it a go and hope it comes out anywhere near that. Cheers, saj