One job in the near future is to respray the entire bonnet on the SD1 due to stone chipping. The existing paint is good otherwise. I'm ok with the actual spraying - well getting better - but would it be best to strip all the old paint first, or is there a magic modern filler I can spray on at home which will be less work?
Have you a random orbital sander, if so (and you are confident in it's use) flat the stone chips with it and then use a high build primer, flat again and then top coat.
What paint will you be using ?
Featheredge the paint around stone chips w/80 grit, fill with glazing putty, block, prime, block, (seal) refinish.
Depending on how much damage there is, knifing stopper?
The orbital sander route is about the best because that will remove the stonechips altogether, If you use ordinary primers they will sink into the recess even acrylic and cellulose stoppers sink when over painted.
Two-pack spray on primer fillers won't sink but you're hardly likely to use those at home.
As an alternative you could use an acrylic polyester spray filler that builds up very thick and quickly which can be wet flatted with 180 initially then use a rubber block until you get to the desired level. Polyester filler is also a two component spray filler but without the isocyanate content.
Though it's probably quicker and easier to use an orbital sander because you won't get any sinkage then as the chips are completely removed and you can build up with cellulose primer without fear of sinkage.
Sinkage or fried eggs especially show up on black paint and Cellulose is notorious for showing up sinkages on repaired panels because it's a soft substrate.
One thing you'll need to watch his not to build up a line of filler or primer across the bonnet as no amount of flatting will remove it, the primer/filler should be sprayed progressively further across the panel with each coat so to blend the paint thickness across the panel evenly.
Steve.
I've got a random orbit sander, but by the time I've removed all the chips I'd be down to bare metal - it was a secondhand bonnet which I think may have been badly stored or handled, as there are chips all over it as well as the front. But it appears undamaged panel wise.
(the welding on the original failed)
Same as original - black cellulose.
Dave
I would take heed of what Steve has said as its the most accurate.
Black will make matters worse if its not done correctly.
I have found that modern paints Acrylic lacquer will sink more than the old ones. I painted an MG of recent and taking it back to metal building it up with filler and primer and 2 week drying rubbing back more primer etc was not a rush. The colour paint still sunk as you can see where a hard top has previously been on the car.
I would next time use a 2 pack primer that is hard.
rm
[snip]
Adding to what I've previously said,
I've just made a couple of JPEG's of how panel blending should be carried out and uploaded them to my website for those who wish to know how it's done.
"
The "blend2.jpg" shows the dark concentration of paint is right in the centre (where the repair would be) and this should be blended from the centre towards the outside lighter edge.
Either method will avoid building up a paint line or thick edge of paint at the perimeter of a repair.
It is advisable to flat the whole panel in order for the paint etc to stick properly because then each subsequent layer will have something to adhere to.
The blending method should be used with primer, primer fillers, basecoats and top coats when a localised bare metal repair is required even if the whole panel is being painted or lacquered the build up must be faded/blended across the panel to avoid any such paint build up.
Steve.
Dave,
There is only one way if you want to do the job once. Bare metal the top surface of the whole bonnet. With an orbital sander and some course discs it should not take too long. Believe me you will thank me in the end for these words of wisdom.
Dixie
Simple solution: Buy a small quantity of two pack high build primer. Mix a small quantity and using a small artists brush place a drop in each stone chip, repeat if required until all chips are above level of surrounding panel. When completely dry block down level with surrounding paintwork and key over remainder of panel with 240 production paper on a sander. Then apply a couple of coats of cellulose primer and sand with 600 paper using a "witness" coat. If you break through anywhere prime again and repeat. When perfectly flat, finish with three or four good coats of cellulose gloss, flat by hand with 1200 wet then finish with G3 followed by G10 on a medium sponge. Only use the very best thinners throughout and make sure your airlines are free from any condensattion! This way you get the advantage of 2-pack build and resistance to sinking without the hazard associated with spraying it.
Gaspode
This doesn't deal with the broken paint edge which may be detached from the panel nor does it allow you to follow back any rust scab that may have formed under the surrounding paint. A thorough feathering out of the surrounding paint using a DA is the best way.
I've never used two pack, but wouldn't it be a problem buying small quantities of it?
Depends on how much is a 'small quantity' and if you know the right person Dave......
I'm inclined to do this, but one thing puts me off - if it's been repaired before, and there is a skim of filler anywhere. At the moment, it looks fine - no ripples etc - just the chips.
;-)
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