Spraying over existing paintwork

[Brabham]

Hi,

  I have a rear hatch that I want to respray however I only want to spray over the existing paint at this stage. The paint has crazed and flaked off in some areas leaving only the primer exposed.

 

My conclusion for spraying over the paintwork would be to give it a light sand and fill any paint chipped areas with stopping putty before respraying the panel. Would people recommend acylic, enamel or 2-pak for the respray and is this the right way to go about it? Thanks.

[xa1973]

Hello Mate

 

As its only the hatch your painting at the moment ( not a very large area ) sand it all back to the base primer, reprime it and paint it with acrylic....1/2 lt base colour will be heaps....

 

If your only after a quick easy and cheap fix this is the way to go....if you muck up, just sand it back and respray again 

 

 

 

[zzzzed]

you may find that with in time the cracks will show through the new paint in time

the best way is to sand the cracks and chips right out. Its dosnt take that much more effort

if you don't like sanding then use stripper, but keep in mind this is messy especialywith acrylic paint

 

as far as the acrylic vs 2 pack debate there was discussion on this topic earlier this week.

acrylic is better for the in experienced painter but is a bit more work to get to finished result.

2 pack will last much longer than acrylic and has a shine right of the gun,

where as acrylic usually need to be buffed

 

 

 

 

[reverendzed]

Like some of the guys said, you need to get beyond any of the crazed or flawed exisiting painwork.  But beyond that, it is my opinion after restoring quite a few older cars that if you want it to last more than 24 months you need to take it back to metal which means going beyond the primer.  The reason for this is that if the top coat has cracked it has allowed moisture to penetrate into the what is presently the substrate which is the porous primer coat which then begins to breakdown.  By removing this primer coat you now have a substrate that is fresh and can be etched, primed, puttied and topcoated.  If you try and fill the cracks with knifing putty they will be back in 6-12 months.

Hope this helps.

Rev.

[Brabham]

Thanks guys. Rev what is involved with etching and what kind of primer should I use. I am presuming a zinc primer should give good rust protection. Given that the paint has kind of washed/ cracked off I am presuming it was acrylic and that I should probably go acrylic again. Is this a good assumption? Thanks

[zzzzed]

you would use a etch primer on the bare metal that is what etching is. then you  can hit it with a high fill primer.

 

When you prepare primer for top coat you should block it back with 180 grit dry sand paper to remove the peal, then 320 dry to remove the 180 scratches, then finish with 600 or 800 g wet and dry for the final coat.

 

I usual use a very week paint mix to make a guide coat which i wipe on with a clean rag this will show all the sanding scratches and highs and lows