Paint Cracking On Polycarbonate Shells

[JeepnMike]

This is my 2nd DB01 shell that has had a horrid case of the paint cracking and falling off. I think I may be able to salvage this one going forward, but it leads me to seeking advice. I thoroughly wash and dry my shells before paint so I know it isn't residual mold grease. I am not too keen on sanding because I know I would mess up and end up scouring the window area. My shells do take a bit of a beatings at the track so I know that doesn't help, I just don't get why the paint flakes like it does. Maybe it is just the Tamiya PS paint I am using? I know the Parma paint on my TB03 shell seems a lot more flexible.

If anybody has any tips to prevent the cracking, I sure would appreciate it.. I feel like I am "wasting" shells.

Thanks!!

[pizzachaude]

Sanding does make a big difference, the tiny scratches get filled with the paint and makes it much harder for it to just flake off

[bigoggy]

I never sand lexan shells, and never get flaking.

Are you spraying in a warm area,?

[InsaneJim69]

I gently sand all my polycarbonate bodies inside prior to painting. It does help alot to help the paint grip the body. For general running you will probably never get flaking issues. But when racing or running very hard with.impacts and vibrations etc thats when you can get flaking from areas where the paint hasnt adhered properly.

When sanding all you need is some 1000 wet and dry. Your not looking to kill the body just a gentle rub over. You can mask the windows and then use the wet and dry as it wont go through the masking tape. Remove wash , dry , mask and paint.

James

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[JeepnMike]

Thanks for the replies guys. It sounds like I need to bite the bullet and start sanding a little. The shells I have painted were in summer so it was warm. Have you guys noticed Tamiya PS paint flaking more than any others? Would a back-coating of black or white (depending on the color) help?

Thanks!

[InsaneJim69]

I only ever had Tamiya ps paint flake once on a focus wrc body. The white seemed to flake very easilly. After that i always sanded and never had an issue after that.

James

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[bromvw]

This might be a little off the wall but it '' could '' be a solution to flaking paint . Why not back the colour coat with a layer of plasticoat ? Strong and remains flexible .

Just a idea .

[JeepnMike]

I think I may give that a try on my next shell. I will also try using Parma paint and see what happens. I have always like Tamiya PS paint, it just hasn't fared well on a race buggy that crashes more than I would like it to.

Thanks for the replies guys!

[speedy_w_beans]

Awhile ago Yello mentioned he had used vinyl & fabric paint you can find at the auto parts store, and he reported good success with it. That might be something else to try instead of polycarbonate paints. It just depends on what color you're after.

Edit: Also, as bromvw points out, the Plasti-dip / Plasticote paints might be interesting too. They're pretty flexible so they won't crack, and they should peel off if you want to change colors later.

[WillyChang]

your paint is chipping off in chunks and also ripping at the masked seams

this suggests you're painting too thick + not letting the paint key in properly before building layers up

i use PS nearly exclusively unless there's no other choice in rattlecan

i don't bother using sandpaper but its worthwhile giving it a scuff with the green kitchen scourer whilst degreasing.

Only time avoid scuffing is when you're using mirror-shine chromes & nano particle flake paint.

before warm the shell AND the paintcan, gotta be at least temperature of your skin.

Keep paintcan warm by keeping it in my pants pocket inbetween coats.

First coat... do a quick 1pass mist, you'll barely be able to see it.

It'll seal in your masking edges better, won't seep under.

Paint needs to cure fully so it keys in so leave it for 5-10mins - walk away, just let the shell be!

When you come back... you can try scraping the painted area with fingernail,

if its done curing properly you shouldn't be able to do any damage.

Now you can paint further coats however you like... doesn't matter,

but multiple thin coats will cure faster than one thick layer.

Avoid drips, if only to avoid wasting paint and making a big mess.

You only need enough to have proper coverage, any extra is waste.

Back with white/black/silver/gold if your colourcoat is translucent or candy,

different backing can affect topcoat shade.

Sometimes then black on top at end as a blockout coat,

if colour can be seen thru windows.

Finally tint with PS31 Smoke on the windows if required.

[AndyjcClod]

I have got exactly the same issue for the first time ever. I have been building and painting RC cars and bodies for 25+ years.

It was on my Neo Scorcher I got for Christmas. I decided to use Tamiya neon orange polycarbonate paint.

It looked pretty good to start (Its in my Showroom if you want to look) but after the first use the paint has began to flakeoff the body badly.

I was told at a club I attend its because lead has gone from their ps paints but not sure if that's true or the cause.

I am thinking of complaining to Tamiya as its not as if the body's or ps paints are cheap and they in my opinion are not fir for purpose.

[Percymon]

Translucent Tamiya PS paints are apparently very prone to flaking, no matter what you do with the body prep

[JeepnMike]

In the two shells I have painted and both flaked, one was with Tamiya PS Flourescent Orange, and the other was Tamiya PS Flourescent Red. Maybe there is something in the make-up of flourescent paint that causes it to be brittle? I should quit painting my buggies so bright... LOL. I just like to be able to see them on the track.

BTW, thanks for the great advice Willy!! I could definitely use more patience.

[InsaneJim69]

Yes thinking back now i have had a few flourescent tamiya paints flake on me. My mazda 787b racer from years back got rid of around 90% of its flourescent orange paint after only 1 flip and roll. it literally ended up with orange flakes all over the track with only the brush painted park green left on the body. i also found the flourescents to take an eternity to dry compared to the normal flat colours.

James

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[WillyChang]

i don't buy/use fluoro lexan paint... if you need to 'see' your car on the track, you're not going fast enough

been given shells painted fluoro, most are backed with white.

None have flaked noticeably more than others.

Translucent Tamiya PS paints are apparently very prone to flaking, no matter what you do with the body prep

bought them by the crate when they first came out... experimented from thin mist coats

to absolutely lathering it on to the point of dripping for max candy effect.

Most of those jobs are still around, hasn't failed.

Same with the Anodised Aluminium colours that came after. Occasionally there's odd flaking

but the Ano colour is stuck on, its the black PS5 that flakes off first... dunno how to avoid that.

[EddScott]

Was going to start a new thread about shell painting but here will do.

What do you do when you are painting a shell and the paint won't stick in the corners of the shell?

I've just sprayed an Astute shell but the paint won't go into the edges of the roof. Not sure how to explain it, its like no matter how many layers I put on the paint won't go into the corners.

[bromvw]

Sound as though there is some contaminate there mate . Give it a really good wash and dry before trying to spray it again .

[WillyChang]

Yeah especially in the corners is where you've gotta really poke your soapy sponge.

Another nasty contaminant is silicone oil, anything from shock oils to hairspray is evil.

[Theibault]

The floro paints must be backed. Ive had a lot of experience with them and if you dont back them, they will flake. The tip in regards to painting in light coats is also key. Too heavy a coat and no backing, it will flake.

[ChrisRx718]

I'm pretty sure it says about backing the fluorescent paints in white on the tin lid?

The factory pre-finished Arta NSX body (fluro red) was backed with white when we sold them.

[JeepnMike]

I'm pretty sure it says about backing the fluorescent paints in white on the tin lid?

The factory pre-finished Arta NSX body (fluro red) was backed with white when we sold them.

I just ran out to the garage to check.. I was going to laugh at myself if the directions or lid said to back it with white.. I am horrible about reading directions for stuff like this.. lol. It actually didn't say it. but as you will see in my pic, I heeded your advice and a few of the others here and will be backing it with white this time. I am hoping to scuff the spots that have chipped, paint it again with florescent red again, back it with PS White, and hope it sticks. I will scuff the next shell too. This shell already has a bit of abuse so it isn't going to look all that great when done, the DB01 shells are starting to get a little rare so I am going to try to make this one last as long as I can (I have another new one just to hoard a bit).

[AndyjcClod]

I have the same issue as below..

(This pics are after its first use and it wasnt even a bashing session!) This was backed with PS1 white.

I have complained to Tamiya so will wait and see if I get a response, annoying that it has pretty much wrecked a new body

[bromvw]

I seem to remember reading that some time ago Tamiya changed the formulation on these paints in order to comply with European rules on the contents of paints and to remove certain toxins . They removed all the old stock from retail outlets as I recall . Maybe the new formulation now lacks the - grip - that the old one did .?

[Yello]

I've used some Parma paints on my Baldre shell prepped with light sanding and the paint is seperating/cracking, and the paint there was backed properly.

I personally don't care to use hobby-specific or pc-specific paint, especially considering the price.

Awhile ago Yello mentioned he had used vinyl & fabric paint you can find at the auto parts store, and he reported good success with it. That might be something else to try instead of polycarbonate paints. It just depends on what color you're after.

Seems like ANY vinyl & fabric paint would be EXCELLENT for RCs. The brand I used was Duplicolor - I've used their gloss black and their red. They are perfect for RC lexan, but there's not much of a selection of colors. I don't even like Duplicolor paint in general so I can only imagine how much better other brands of vinyl paint would be. Rustoleum make a line of v&f paint too.

Speaking of Rustoleum, I've noticed every color of their auto paint - gold and white - that I've used on Lexan have resulted in 0 cracking/seperation. Rustoleum make good spray paint and their paints tend to be very tacky - oily and thick. I'd venture to say any Rustoleum spray would probably work very well on lexan.

Edit: Also, as bromvw points out, the Plasti-dip / Plasticote paints might be interesting too. They're pretty flexible so they won't crack, and they should peel off if you want to change colors later.

I've used the Armor-All version of plastidip for rocker panels it's held up well, all things considered.

On the wheels, I've used the name brand Plastidip black paint, and after a while the paint looks like **** - like dirty, dingy garbage bags. I don't recommend it.

[TongueTied]

Try AutoAir Colors. Very flexible and works great on lexan. I've had no issues with cracking or flaking. You can also get it in just about any colour imaginable and if not, you can mix it easily. Only downside it that it doesn't come in a rattle can