15 replies to this topic

[RAMPAGE]

Hey guys,

I am at the stage of priming my mini. I have sanded it all back and done what i needed to do with rust and stuff. When i spray the primer on the body it lifts in little patches and its getting really annoying. does anybody know why this is happening and how can i fix this?

Thanks.

[Hekmat]

It sounds like the primer is reacting to something on the surface, most probably is grease/oil. Try using some alcohol whips. Also make sure the primer has something to stick too, if the surface is too smooth it will not stick, sand down the areas with a 240g.

[RAMPAGE]

I thought it would need somthing gritier than 240 and is methelated spirits good for cleaning?

[panelbeaterpeter]

Primer will stick fine to anything upto 2000 grit, but ideally you should prime over 320, or down to 180 if you're using high build primer. Is it wrinkling? if so, it sounds like a chemical reaction, usually caused my insufficient degreasing or incompatible paints, or you may simply be applying the first few coats too thickly. You should always apply a very thin coat first, and let it almost dry before applying any further coats, this acts as a sealer coat and stops the solvents in the primer attacking the paint underneath. If that doesn't work, try sealing it using barcoat prior to primer, alternatively mix 2k hardener 50:50 with 2k thinners, and apply that very thinly, usually does the same job. Oh and you should be degreasing with panelwipe, or degreaser, try to avoid the engine type degreaser, it tends to take ages to dry and gets stuck in crevices. I've never tried meths..

Edited by panelbeaterpeter, 13 September 2009 - 09:38 AM.

[little_rarfy]

ive just primered my boot area on friday and its done exactly the same in certain places. i did panel wipe it before i primered it so god know. will be flattening it down tomorrow and giveit another shot. hopefully be ok.

[joakwin]

could be oils on the metal or if the temp where you are painting is to cold

[panelbeaterpeter]

could be oils on the metal or if the temp where you are painting is to cold

Oils in the metal?? primer wouldn't react even if it's freezing unless there was ice on the surface..

[RAMPAGE]

Thanks for all the good advice guys. So should i sand back what i have already sprayed, give it a good clean then try again?

[Hekmat]

If the rest of the area is dry and solid leave it alone, just sand the effected area and around it say about 1-2" give it a good wash (warm water) and "Panel wipe" to remove small particles of sand and paint. Make sure is completely dry before you apply a thin coat of primer. If you can leave it for 2-3 hours and then apply the next coat.

[RAMPAGE]

i tried doing that but when i did it the primer wouldnt stick to the edges of where i sanded.

[martin_stgeorge]

apparently if you have silicon on the metal it will not let the primer adhere, do not ask me how to get it off of the car, but if you use tire black that contains it, even if you have rubbed down the car it can still be in the metel, i don not know how to neutralize it but i suppose if you look on the net you might get your answer.

[midridge2]

i think there could be a problem with the primer in some cases, i did a bare metal respray on mine awhile back and when i primed the front end the primer just rubbed off with your hand every were, i again used spirit wipe and tried again, same result, i tried a new primer and fine.

the primer was tetrosyl sp cellulose.

[panelbeaterpeter]

If the rest of the area is dry and solid leave it alone, just sand the effected area and around it say about 1-2" give it a good wash (warm water) and "Panel wipe" to remove small particles of sand and paint. Make sure is completely dry before you apply a thin coat of primer. If you can leave it for 2-3 hours and then apply the next coat.

Don't wash it with water. Primer is porous and will soak up the moisture, causing micro blistering either when you paint it or a while after.

[RAMPAGE]

If i spray the pimer with laquer will it stop the water getting soaked in?

[RAMPAGE]

If i spray the pimer with laquer will it stop the water getting soaked in?