problem with spray painting

[swansty]

im respraying a car and have just started to put the paint on top of the primer. there seem to be very small spots forming where the paint isnt sticking so im getting little grey specks of primer showing through. while im not looking or expecting a super finish, i was wondering if anyone knew what causes this and how i can rectify it. cheers

 

[Jason]

silicone reacting with it causing fish eyes...

 

[swansty]

the primer was rubbed down and dried before painting. any idea where the silicone is coming from?

 

[excursion]

did you use ultra fine sand paper mate? when i de-badged my car i got the same problem. i had to buy ultra fine sand paper and go at it for ages.

 

[pablo]

when painting over the primer do one quick skim of a coat. let that dry then add a couple more coats. might help u.

u got water traps in the airline too?

 

[swansty]

i used 600 grit wet. was told not to go any finer than this before painting and that either 400 or 600 gril is most suitable. most of the paint is grand, just tiny little spots.

 

[Con]

keep rubbing down with 2000 grit. it may take a bit of work but keep at it. the aim is to remove ALL imperfections even those u cant see

 

[ANDYBL4IR]

Is the car spot primed, ie just the repairs primed. If it is and you have used cellulose primer and 2k paint you will get a reaction around the edge of the repair. If it is silicone it could be in the air in the shed you are painting in, or the sand paper could have been sitting near the pollish? did you panel wipe the area to be painted first?

 

[swansty]

@pablo: no water traps. i realise this may be a problem but was hoping to get away with it.

@andybl41r: its a complete respray and yeah its cellulose primer and 2k paint. surely i wouldnt have been sold the 2 together if they were going to react? the spots are all over. cant think why any slicone would be in the air and the paper was just bought. panel was wiped clean before i started but just with a cloth.

 

[Jason]

panel wipe is needed though to properly clean the area.. your hardly going to remove years of silcone from polish's with just a wipe

 

[ANDYBL4IR]

you may need to let the coat of paint dry now, flat it down and paint it again. It should be ok then because you will have sealed the surface.

 

[swansty]

where is the silicone coming from on frshly primed panels? prior to priming, i rubbed everything right down. will look at getting these panel wipes though

 

[swansty]

@andy: yeah im going to see what it looks like in the morning. then maybe play about with a wing to see if i can improve the finish any.

 

[ANDYBL4IR]

It could be coming from around the moldings, door gaps anywhere really. It wii blow out from places like these if they are not properly taped up

 

[swansty]

all panels are off so its just metal. they are even on the wings and bonnet which dont have any mouldings. its a bit frustrating to put this much work in and then get we problems but only my first time painting so i will live and learn!!

 

[excursion]

fire up a pic mate, it might be something more obvous to us if we can see the problem.

 

[gixerboy]

where is the silicone coming from on frshly primed panels? prior to priming, i rubbed everything right down. will look at getting these panel wipes though

All panels need to be degreased with panel wipe (available in 5lt tins & wear latex gloves) even the oil from your skin can cause paint reactions..

 

[Pocket_rocket]

your setting fish eyes indeed but whether its caused by silicons or water there is no way to check, panel wipe MIGHT help you out but its something i dont use very often. normally cleaning the panels down with thinners prior to priming them and keeping then panels bloody clean is good enough. just wear cloves and dont let your sweaty skin near the panel. if you have no water trap what way are you adjusting the pressure? go tomorrow and get a water trap water in the airlines will break your heart and even if you get the fisheyes covered they will be noticable in the finished job.
the first few coats of colour you put on should be patchy and dont cover lots, these coats are just for adhesion, do two of these dry coats and then put on a wet coat to join it all together. this is assuming your doing a clear over base paintjob and using laquer over your colour. if your getting fish eyes in a solid colour your gonna have some fun rubbing it all down again before recoating.
additives can be bought to lessen the likelyhood of silicon problems but its something i have never needed to use, your more than likely getting water condensation in the airlines.

 

[swansty]

i think it was water all right but wiping down the panels with white spirits seemed to help with most of them. it only a nav rally car and my first attempt so a perfect finished was neither required nor expected. its all finished now anyways but thanks to everyone for the help. it was all appreciated.