10 replies to this topic

[TheHippo]

Hi,

 

I've just resprayed my car with celly, with the roof a different colour to the body.

 

All surfaces (roof and body) had the same prep (old paint sanded back, several (4?) coats of high build and standard primer, tacked, panel wiped), the only difference is that I painted the body from a gun whilst the roof was done with aerosols. The body paint has taken really well, no reactions. The same can't be said for the roof unfortunately.

 

When I was laying the roof paint on it looked fine - a nice, even coat and it stayed that way for about 24 hours. When I then went back out to the car the next day there were about 5 or 6 blisters and cracking in random spots on the roof. I'm not talking wet blistering, this was really dry, flaky paint. I sanded the whole roof with 1200 and it all came up fairly smooth (with exception of the patches). I then left it until the next day, when I went back to find a couple more of the patches had appeared. There were some areas that were sanded back to bare metal, but not all of it, but the location of the flaking has no correlation to this.

 

I don't know whether the reaction has something to do with the fact that it came from rattle cans or not, but other than that it was painted under exactly the same conditions as the bodywork. I might also mention that the roof has never painted up very well - the bloke who had the car before me had done it and it was a rubbish finish, so I redid it about 18 months ago (that time with a compressor) and again the paint just didn't want to come up well. Even this time, when the paint was fresh, it was quite a rough finish but I'm confident it would have sanded and compounded quite smooth.

 

The point of my post, really, is to ask what people could suggest by way of some sort of 'sealant' that I could put on the roof so that when I repaint it there's a better chance of it actually working. I've heard about stopper and knifing putty, but this seems to be more of a filler, where I'm sort of looking for something I can spray on that will form a barrier between whatever may be on the roof causing a reaction, and the new paint.

 

I'm hoping someone may have an answer as it's really annoying me that I've put so much effort in and it hasn't really paid off.

 

Thanks in advance (and hope...),

 

Dan

TheHippo

[cookie4343]

You could try Barcoat or take down to bare metal etch prime, prime then paint.
http://www.ebay.co.u...PAAAOSwBLlU1gcf

Edited by cookie4343, 04 April 2016 - 10:32 AM.

[jaydee]

Rattle cans needs to be sprayed a lot finer, try very thin coats and let the paint dry out few minutes more than you did before. Dont warry about the finish at this stage, it will need to be flattened back with G3 or 3M later.

Cleaning surfaces thoroughly with spirit like ethyl alcohol should be fine to avoid contamination.

[Stu.]

Dan, This would be my suggestion -

 

Gather up all you're rattle cans and bin them.

 

Flat the roof paint back ready for primer.

 

Purchase some epoxy primer (I use HB Body 989) and use that from a gun. 2 good coats should be ok.

 

Flat it back once cured and key for topcoat (a couple of days should do it).

 

Progress with you're celly topcoats.

 

Epoxy primers are very stable and I've found they act like a bar coat. The primer wont absorb moisture either so is even better.

 

I had no end of trouble with rattle cans and celly. Since I've been using epoxy primers I've not had one single reaction, and its great to spray and work with.

 

I'm sure you'll get sorted, and I'd highly recommend going down the epoxy road

Edited by Stu., 04 April 2016 - 06:28 PM.

[markyB]

I'm sure most shop bought rattle cans are an acrylic type of paint and that maybe where the problem with the reaction begins ?

[JCP]

As there's always been problems painting the roof, then definitely take it back to bare metal first, as it sounds like contamination of some sort has absorbed into the old paint/primer.

Highly recommend etch and epoxy primers too, I use Spectral under 395, it's the only part of the paint process where aerosols are used,
(However will be trying out HB Body 989 as mentioned in Stu.s post above)

And the big one when painting is be patient, things can go really wrong really quickly, and it's always when finishing off, nothing worse than getting a run in your final coat!

Hope you get it sorted.

[Daz1968]

I have used hb body 989 epoxy and it is very good and builds almost as good as a 2k high build primer sands very easily but doesn't absorb moisture so ideal for home use when top coats are not always applied straight away. It also can be over coated with most paint systems.
Another bonus with epoxy is it sticks really well to bare metal and as it doesn't contain isocyanate you can use a filter respirator,

[cookie4343]

Must try this epoxy, I found rattle can etch didn't work but it was a cheap brand so I brought some to go in the gun, the etch I have would knock you out without a mask.

Might try epoxy on my next project.

[TheHippo]

Thanks for all the replies. I'm going to try Barcoat, then priming and painting from a gun.

Just to clarify, as questioned by markyB, that the aerosols I had used were celly.

 

Fingers crossed the Barcoat will work, but if not then I will take back to metal and etch/epoxy prime...

 

Thanks again,

 

Dan

TheHippo

[Cooperman]

Barcoat will be your friend. After spraying it don't flat it back. Just apply a high-build primer, lightly flat that back and spray top coats.

[MIGLIACARS]

rattle cans react with themselves   there like a women with pmt

 

there full of thinners.

 

gun everytime