Disclaimer: I do not care what you saw on YouTube or read on forums all over the web, painting is not easy, and the materials you are handling can shorten your life cycle if you are not ultra careful.
Quote:
Originally Posted by 767Jockey
First off, in full disclosure: This is not for my Cobra. My older (2005) motorhome has the paint basically burned off the crown area over the windshield. The Texas sun has just burned this area up. I'm not sure if this question violates site rules. If so, mods, please delete this. However, even though in this case it's for my motorhome, I believe this can help some guys who might be considering doing paint work on their Cobra's too.
Here we go with the situation and the question:
It appears that the base coat is mostly intact, the majority of the issue is with the clearcoat. However, I doubt the basecoat can be saved. My plan is this - sand with 800 grit until I have a uniform smooth surface. Sand again with 1000 grit to reduce sanding marks. Prime, spray basecoat, spray clearcoat, wet sand, polish and wax. I've got a full array of 3" and 6" random orbit polishers (Griots) as well as a 7" rotary buffing setup to take care of the final polishing, with lots of different grades of pads, compounds, waxes, etc on hand as well.
Questions:
- What primer would be best.
- What grit paper to get down to on the primer before I spray the basecoat.
- HVLP or LVLP gun for the basecoat? This is a small area, about 14 inches tall by 8 feet wide. I'll be using a 25 gallon compressor. Not ideal, I know but the area isn't that big. I want this to come out nice but it doesn't need to be perfect show quality.
- What size tip in the gun and what pressure at the gun to spray basecoat at?
- HVLP or LVLP gun for the clearcoat? Again, pressure and tip size?
- Lets say the base coat comes out with some orange peel. Do I wet sand the basecoat before I clearcoat it, or do I clearcoat right over the orange peeled basecoat and hope the clearcoat evens out visually the orange peel in the base coat, then wet sand the orange peel out of the clearcoat?
Again, I want this to look nice, but I don't need perfection. This area is 13 feet above the ground. It's not like anyone is going to get way up there to examine it closely. It needs to be clean and shiny, that's about it.
Hopefully the answers to this will help some Cobra guys thinking about painting their own cars too.
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Quote:
Originally Posted by MAStuart
First off 800 /1000 grit is way to fine for primer to get a good bite to. Most places would be using 80 to 180 to prep the area for primer. The primer would then be sanded with whatever the paint manufacture calls for. A lot of base coat call for 400 grit but some calls for as fine as 800 grit. Most of the time bass coat is not sanded unless it is screwed up . Then it is usually resprayed then clear coated. If the paint is to be blended into the area around the primed area it needs to be prepped for blending. If the area has hard lines to be painted to after the area has been primed the whole area will be sanded with whatever grit the basecoat calls for.
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420 grit would be the coarsest I'd suggest using, then jump to 600 grit, 600 grit will still give enough bite for the primer without leaving noticeable sanding scratches. Finish the primer with a 800 grit, forget about anything else numerically higher.
As for the OP, since the clear has failed, and the base looks good, you'll still need to sand through the base and primer over, as you do not know if the base had an interaction with the clear, or vice versa causing the issues you now have.
What paint, base/clear of course, you will not need more than 3 quarts of each. As for brand, that depends on your budget and what the local automotive supply house carries. Do not let someone talk you in to this brand or that brand, as there are 30 brands of paint here in the US, and only 3 manufacturers who supply the product to them these days.
Equipment wise, even using a HVLP gun (my last being a set of 5 Sata RP Digitals), paint tip size will depend on the product you choose to use, your 25 gallon compressor will not be sufficient the area you expect to spray. On top of a gun for base, you'll need a separate gun for clear, and a 3rd gun for primer. 100 gallon air compressor (minimum), 3 filter desiccant set up to remove moisture and
oil from the air line leading to the guns. Paint suit (what you are spray can be absorbed in to your skin), proper automotive respirator (what you breath in can kill you). What you have not asked about is also important, you'll need reducers, mixed for the temp and humidity conditions of the hour you actually spray. Without a proper mix, you are throwing your hard earned money away.
Sand
Prime
sand
prime
sand
prime
sand
(repeat until absolutely smooth, paint does not self level and once the clear is on, will show every imperfection you missed)
wipe with tack cloth sprayed with automotive dewaxer/degreaser
wiper with clean tack cloth
mask off (if you don't do this well, you will have overspray on your entire RV and will pay twice as much to have it professionally removed than the cost of having a professional do the paint work in the first place)
wipe down again with a clean tack cloth
spray base (do not let this run, multiple light coats are better than 1 or 2 heavier coats)
Allow to flash over
Spray clear, the same technique applies
Let dry 24 hours (I said let dry 24 hours above 50 degrees, and not in the direct sun)
If no runs, you are done, do not bother to wet sand and buff, if you are not experienced, you'll end up buffing through the clear and have to start the whole process over again.
Wax, NOT FOR 3 MONTHS OF TEMPS ABOVE 48 DEGREES, IF EVER!!!!!!
See, isn't that simple
Bill S.
Retired bodyshop owner