Thread: Painting Tips Required.

Spray cans are mostly thinner and little paint so you'll get a very very thin coat of paint on the job,so it won't offer much protection.
To get 500mil of 2 pack mixed up, some hardener wouldn't cost much.
You can get 2 pack also mixed up in Aerosol cans these days, the hardener is in it you just punch the button at bottom of can to release it. @ pack will be a harder finish and won't rub off easy. ( a small job like this shouldn't poison the lungs too much with 2 pac.
Primer is also avail in 2 pack if you are using a solid solid colour ( not metallic ,then clear coat isn't necessary.)
Re the panel to strip it back to bare will be necessary as you say paint is cracked, there are previous repairs, then stripping might damage the bog repair.
It depends on how good a repair you want. It might be easier to find a good panel elsewhere with a good paint surface and use that as your base with minor prep. Ie degrease, prime over and then top coat.

This is just touch up and repair so I don't want to get into 2 pack paint. Acrylic will do what I need and I've already got it, I'm just not sure on surface prep and compatibility with the primers I've got.

I've done minor repairs a few times and I haven't found it necessary to go to bare metal assuming the paint isn't flaking away or anything silly. It's much more important that it is sanded to a very smooth finish. 800 - 1200 grit. Then like any painting, very clean.

I can only comment on steel painting, not Al. For steel panels I have never used an etch primer.

I don't know specifics about types of primers and suitability, but in the past I have generalised on these things a bit and never had a problem. IE the septone primer is automotive, or at least for acrylic/enamel based paints? They are largely compatible unless you start talking about a primer/paint for a totally different material like wood. On steel I would say clean smooth surface with septone primer, then acrylic colour is all good.

I have mixed my own paint with thinners. A good mix is very thin. If the spray packs are thinned like a typical automotive paint would be, expect a very minimum of 2 coats. Preferrably 3+. The coat will be very thin. If you try to apply a thicker coat, it WILL run if it's thinned appropriately. Don't be surprised if 1 coat barely covered the primer. If it's a touch up repair job, 2 is probably OK. What does the spray pack say? Brand/type?

Aluminium I'm not sure sorry.

When preparing for paint you need to take the crazed area back to bare metal or the crazing will come back through in the top coats.As for soda blasting I have read at of reports with automotive paint not sticking and lifting off at a later time. Acrylic paint will fine and you already have it just put a etch primer down first over bare metal parts


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Since Dougal used a very generic title I feel I can throw in my bit and ignore his more specific comments

Any info will be useful.

I'm about to paint my RRC chassis with a urethane based paint.

The panel paint on my RRC has lots of bubbles. At first I thought it was dreaded oxidisation of the aluminium. I picked away at a couple of the bubbles to find a brownish liquid underneath. Either failing primer or just before top coat some ming on the assembly line opened a can of warm coke that sprayed down the side - well two mings cause its on both sides. Anyone had the same?

I've also bought some top coat to do the Disco vehicles. Would particularly like to know how to get the remaining old top coat off. The failure of the top coat on one vehicle started as tiny pin holes, which then led to raised circles of lifted top coat. The circles joined as they got larger. On close inspection, the original pin holes go right through the top coat, the colour coat and well into the primer.

Originally Posted by workingonit

Since Dougal used a very generic title I feel I can throw in my bit and ignore his more specific comments

Any info will be useful.

I'm about to paint my RRC chassis with a urethane based paint.

The panel paint on my RRC has lots of bubbles. At first I thought it was dreaded oxidisation of the aluminium. I picked away at a couple of the bubbles to find a brownish liquid underneath. Either failing primer or just before top coat some ming on the assembly line opened a can of warm coke that sprayed down the side - well two mings cause its on both sides. Anyone had the same?

I've also bought some top coat to do the Disco vehicles. Would particularly like to know how to get the remaining old top coat off. The failure of the top coat on one vehicle started as tiny pin holes, which then led to raised circles of lifted top coat. The circles joined as they got larger. On close inspection, the original pin holes go right through the top coat, the colour coat and well into the primer.

I wonder if they were some contamination before the original paint. Causing each layer to spread away from the centre.
I know silicone spray is a bastard for doing that, but most oils might.

Check out the condition of the steel behind the panel. It's perfect.

I love living in a dry climate. 30 years and the waxy stuff is still intact on everything. The surface rust on the top of the fuel filler tube is what you'd get in a week on the coast.

The rule with preparing a surface is to leave a good 'key'- for solid colour, leave this in 320 grit.

The rule with crazing paint - some call it crows feet- is to sand all the way to the metal. All crazing paint must be removed.

The rule with bare metal is to use an etch, then primer, then colour then clear coat depending on what combination you are working with (clear over base metallic, clear over base solid, or straight solid).

If you have areas to which you have applied filler, you only need primer on top of this prior to colour. You can buy 'one hit' primer filler- this is ok but leave it for at least a day after applying your last coat before sanding- the longer the better- product shrinkage is an issue. Always use generous flash-off times.
Personally, I use separate product (primer, high fill spray putty). I try to use matching product suppliers- Septone offer the full range relative to acrylic, two pac or enamel. I can't comment whether the septone etch product you have is suitable for acrylic. Ask at the vendor's counter if you have any doubts.

Try to apply the colour over a solid even primer colour- usually it will be grey in colour- the primer colour can influence the appearance of top coat depth. Look for pin ****** sinkage in any fill you have applied. use blade putty to address this, then apply primer and putty over the top of that.

Lastly- there is nothing inherently wrong with spray cans though they are not ideal- they certainly are very handy. If you want depth in the colour, then, to do the R/R quarter panel pictured, have two cans ready and then apply the clear. Remember to dust coat first- leave for at least 30 mins, then steadily apply coats in an overlap pattern- thicker (wetter) as you go. Three to four coats more can be better but risk for reactions increases with more product, and the wetter you apply it (wet=heavy coat)

Also- the chance of reactions happening (the usual cause of crows feet/crazing) increases when you apply your product over that applied in the past. I personally prefer to strip everything off and start again. I haven't used soda stripping before but be wary of any chemical or dipping type strip process- these leave nasty residue.

Cheers and good luck