Unknown original paintwork - Posted: 20th Oct 2010
I'm In the process of restoring a 34" Fireboat that I acquired off ebay.
Unfortunately when trying to spray on an acrylic primer I'm getting an adverse reaction In that the new paint Is bubbling / crackling In some areas. I have no Idea what the original paint was although It looked to have been brushed on.
Any Ideas please for a suitable protective and Inert primer / undercoat that I could use to stop this reaction.
Had the same problem with my Arun. I have used many types of acrylic spray paint but try to avoid the rather costly Halfords. Mostly the cheaper cans available at discount outlets and markets/car boot sales are OK. However I was told by my regular supplier that the cans have a shelf life (not marked on the cans) and over time the propellant/solvent does not fully dissolve the paint. As a result the spray contains excess solvent which may attack whatever paint lies underneath. Net result Is a crazed paint job. I had to completely strip my model down to the fiberglass and start again, rubbing the affected areas with wet and dry did not work as the underlying coats had all softened and would not dry without crazing. Thinking back I seem to recall the faulty spray was thinner/ less dense than previous applications and on checking my supplies I found that the whole batch was similar and unusable. I always shake my spray cans for the required 2 minutes but this has no effect on faulty cans. As you have possibly already softened the underlying paint I do not know of any primer you can apply that will fix the problem. If you do find a solution please post details. Dave
The paint problems you are getting could be a bad reaction between two different types of paint. If you have a car paint mixing shop near you, there Is a primer sealer that you can buy to avoid this kind of reaction, you have to apply a coat all over and not leave any gaps and then your top coat should go on blister free.
I used to restore old cars and always used primer sealer before applying any paint and causing me hours of rubbing down. It could always be that you are applying far too much paint at once, lots of fine coats are much better.
Good luck with fixing your paint problems.
the correct automotive sealing primer Is BARCOAT available In litre tins , to be sprayed straight from the tin , Ie no thinning required ! not only will It stop the reaction with old / unknown paints It also stops the bleeding effect when your trying to overpaint something that was previously red . this works very well , I too work within the motor trade & have found It a saviour on many occasions ! jon
I have read the Info sheets on both the products suggested. A clean solid surface Is required for both so If like me you have already damaged the subcoats then you will need to wet and dry to a firm surface. This was my problem, and I suspect yours, as the subsurface was rubbery and absolutely refused to set or sand to a smooth surface. I,m sure both products will protect a good prepared surface before any other paint Is applied, but I suspect neither will rescue a damaged surface. It will be Interesting to hear how you progressed.
You can paint laquer over enamel ,but I would suggest going back to the base wood.Use a primer sealer to seal all the other paints out then go from there.I know what your talking about,happened to me till I figured out how to deal with it.Ive even gone as far as to brush on a couple layers of 30min epoxy deluted 50% with denatured alcohol to use as a sealer then start my primers to get smooth.Do Not Paint Enamel over Laquer,the enamel takes a long time to dry which attacks the under layment of any paint/primer.This is why the bubbles form under the paint you just put on