Attempt to repaint roof

[sullygully]

Ok, well as some may now in an earlier thread, I wanted to get my roof and hood repainted because of some rock chips and scratches.
I still haven't had a chance to come into the city to get a quote, but I will tomorrow.
In the meantime, I've been doing a lot of research about DIY.
I'd really like to attempt to do the roof. I figured if i'm not happy with the out come, then the worst that'll happen is i'll just take it in to get it done professionally.

So my questions are as follows:

1) Can I sand down to the existing primer, and begin to spray my topcoat, or do I need to reprime over the existing primer?
My roof has some really deap scratches, some just in the clear coat, and some into the primer, but nothing is down to metal.

2) Before I spray the clearcoat, how long is needed to wait to do this after spraying the topcoat, and what would be too long?

3) Also, do I need to clean or sand the finally topcoat layer, before adding clear.

Thanks for your help

P.S. One reason i want to try it myself is a pride thing I guess. Its become quite a hobby working on my car and I just want to do as much as I can for that added experience, and for the joy of accomplishing it myself.
Money is partially an issue, and if i'm happy with the outcome then it just opens the window for me to attemp other things like the hood, therefore reducing labour costs.
But like I said above, I plan to get it done either way, so its more for the experience is all.

[ninspeed]

1) Can I sand down to the existing primer, and begin to spray my topcoat, or do I need to reprime over the existing primer?
My roof has some really deap scratches, some just in the clear coat, and some into the primer, but nothing is down to metal.
You can, but you will still see some of the scratches... i suggest a coat of a high build primer, and block it out with a guide coat



2) Before I spray the clearcoat, how long is needed to wait to do this after spraying the topcoat, and what would be too long?
let the base coat flash off (5-10 minutes depedning on temp).. most base/clears say no longer than 20hrs before the top coat needs to be sanded, and reshot



3) Also, do I need to clean or sand the finally topcoat layer, before adding clear.
No, you can take a tac rag to the top coat if it is flashed off.. but i would not suggest it for a DIY'er

It may be a pride thing, but it takes alot of pratice before you can lay paint and clears down well... and even longer to learn tricks incase something goes wrong (and no matter how good you are, or how long you do it, you will allways run paint ect...)

[sullygully]

Thanks alot for the advice, I really appreciate it.
I just bought a gun and will be getting the supplies soon.
I plan to practice on some scrap sheets of metal to get the handle on it, before I take it to the car.
My boss and are going to make a make shift paint both at our shop. He has a 1977 Civic that he and his son are restoring, and plans to paint his self as well.

I thinking about just sanding down the scratched spots, and then laying some coats of primer to build it up to the rest of the surrounding paint. Then sand the entire roof, but only to scuff the paint.
I read somewhere that paint adheres very well to the original paint if its scuffed up(sanded).
I just wanted to get a second opinion.
Is this just the easy way out, or is it just as good as just sanding the entire roof down to primer?

[DuPont]

Theres no need to go deeper than the scratches go (you said none are past the primer) So sand the scratches out, primer the spots that go into the original primer, block-out those areas using a guide coat, and sand the rest of the roof with 400.

Factory primer or E-coat is WAY better than anything a DIY'er or even a shop would normally use.

Another thing to keep in mind is that flash times are directly related to temperature. A real paintbooth(1.5 million BTU) has 100s of cu.ft/min of heated air drying the paint/clear. So flash times are a lot shorter than in a garage "booth" Basecoat is more forgiving for short flash times, but clear will run to the floor if you rush it. Your roof is horizontal/flat so it's not as big a deal as say a fender or door.
Easy way to check if clear has flashed is: stick your finger in the clear on the masking paper. If it has flashed, it sticks to your finger, and is "stringy" as you slowly pull your finger away. If its still runny, and doesn't follow your finger off of the paper it's not ready yet.

may the force be with you, and have fun.;)

[sullygully]

Thanks dupont, and ninspeed, for the helpful advice and support. I'll make sure to put an update on how it all went. Hopefully it will be positive outcome.

[Moe Man]

make sure the paint you are using is compatible with the paint that is on your car, or it will just bubble and wrikle up

[sullygully]

Well I finally got around to painting my roof.

I used Duponts Chroma Base and Chroma Clear.

Overall i'm pretty happy, unfortunately the mosquitoes desided to come out and got into the shop, and two of them landed in the second coat of paint. So i've got a couple little blemishes where I had to pick them out. Other then that It looks great. Well see how it looks after I compound and polish it.

Heres a pic. Its got some dust on it, and the $90 digital camera doesnt capture the picture too well, but its just to give you an idea how it turned out

http://memimage.cardomain.net/member_images/7/web/331000-331999/331468_66_full.jpg

I'll probably attempt my hood next. I just want to compound and polish the roof first, and see how the final product looks before I go any further.

Feel free to comment or if you have any questions, i'm all ears.

[A790]

That's not bad, especially as a first shot!

[danno567]

Way to go!

Good Job!

how much for the materials ?

[civicrider]

hard to see but from the pic it looks good. did you get any orange peel in the clear?

[sullygully]

Thank guys.

The base(pint), basemaker(litre), clear(litre), and activator(1/2 pint) came to $115 from UAP/NAPA Paint Division. Pretty good deal considering I only used half of the materials. So I have enough left to do the hood. HVLP Paint gun was $50 off ebay, plus supplies($20).
So $185 in total for a hood and roof job.
Pretty good considering I got quoted $300 just for the roof from a Canmore body shop.

Its has some faint orange peel yes, but i'm hoping with some polishing or 2000 grit will clean it up a little. But its not noticeable unless you stick your nose right in it.

I should have taken a before piture to show you how it looked before with all the scraches and chips. If you saw what it looked like, you'd have an even more appreciation for it. Thats why i'm pretty happy, I can deel with a little orange peel anyday. lol

[civicrider]

what kind of gun did you use? what tip size?

[sullygully]

The gun is made by NativeArts. I'm sure you've never herd of it as neither have I. Its one of those guns that I think is mass produced, sold to other companys, and they just put their name on it.
It has a 1.4 tip.

[DuPont]

Looks good:thumbsup:
I was wondering how this turned out for you.
And your right, NO one will see the defects unless you point them out, or they're rubbing their face on your roof. A little wetsanding, and some polish, and it'll look better than new.
Good job.