spraying

[les]

I sprayed my van cab roof about 4 years back, but due to getting a few marks during restoring the rest of it I want to respray it again. My question is this-- Option 1, rub down the existing top coat and spray another celly top coat on.
Option 2, as 1 but spray undercoat again followed by top coat?
Looking forward to your views.

[mogbob]

Les
Depends on how coats you laid down last time and how well the ravages of English weather/ external damage has taken place since.
Are the " marks " surface rubs or proper dings/dents/real visible scrapes ? If it's broken the paint surface and you need to rub back to metal then rust treatment, primer layers and then top coat again.keep the area being rubbed down to a minimum, consistant with a good blending / finish and avoid rubbing the vunerable edges of the roof too hard.

People look at the quality of the paintwork after a resto and the cab roof is not a massive area to prep.You've got the skills
and equipment.
You'll kick yourself, if you don't, and spend years mumbling to yourself " I wish I'd .... it looks a bit second rate, compared to the rest"

My six pen'th.
Bob

[les]

Ok Bob thanks, the van has been dry all this time (in garage) and minimal damage, but you're right, I think I will body stop any scratches/marks, rub down apply a modest amount of primer and take it from there.

[Longdog]

I would flat with 800 grit with soap to provide a good key and then spray top coat straight on. If you undercoat you will have a line where the two come together. If you still have a batch of the original paint make sure you give it a good stir as some of the pigment settles out over time and you can end up with a very different shade.

[Longdog]

Sorry meant to add spot prime where stopper is used

[les]

Thanks, I need to give this a good dose of thinking, now option 1 AND 2 have been offered.

[kennatt]

If you can avoid putting primer on do so if the marks can be rubbed out without going through to the primer, If you use primer there is a very good chance of the top coat sort of lifting the edge of the primed area (Dosent matter how well the edges have been feathered) and you will see the spot primed areas especially on roof and bonnet,no amount of polishing will get rid of the rings.Better to prime the whole roof,or use 2pack primer which the celly(Presume thats what you are using)will not react with.Been there with a bonnet three or four goes,then a strip back to metal and start over again,Good luck

[bmcecosse]

As above - if the marks rub down without going through, then just flat all over and apply one good heavy coat of colour, followed by a light thin coat to bring up the shine !

[les]

Decision made, as the roof has a few areas where it breaks through to primer, I'm going to rub down and prime all over first. Thanks for all your replies.