Where to mask edges when painting?

[Doug_B_928]

I'm a newbie to car restoration and am restoring my first car, which is a 1973 Porsche 914. It's a complete basket case. It's too cold here to work on the car during the winter, so I spend my 'car time' at this time of year researching. I'm planning to paint the parts that people don't really see (trunks, wheel wells, underbody, underside of hood and trunk lid) myself and probably have the rest professionally painted. My question is, when I paint the underside of the hood and trunk lid, where is the best place to mask and do I roll the tape over to try to get a soft edge?

[Fast Freddy 944]

If its a surface re-spray just mask off quarter panels, door jams. Cover your motor and door jams and trunk area with brown wrapping paper. If you are doing a concourse style paint job, pull every thing off, motor, electrics, trim, strip it down to metal then prep, mask and paint......

[Doug_B_928]

Thanks for your reply. The car is almost completely stripped. I'll be doing a lot of metal work as it is quite rusty (I'll be replacing rear quarters, trunk section, outer longs etc). Because I've never painted and don't have a paint booth the plan is to leave the most important parts to a pro, but I want to learn and like to DIY (and have a budget) so I'll do the parts that aren't so visible. Given that the hood and trunk lid tops will be painted at a different time than the bottoms, on which part of the edge of these panels should I mask? That is, do I do the bottom of the edge of the hood so when the top gets professionally sprayed the edge of the hood will also get sprayed? Do I back mask it for a softer edge or what's the technique to deal with edge when painting the top and bottom of a panel at different times?

[Pauld_94S2]

Doug, the best course of action would be to select who you are going to have the finish paint done by and take their recommendations.

If you haven't chosen anyone, visits a few shops and get their comments.

Also, you need to be careful that paint you use is compatible with what the body shop uses and that the color will match. Unless you are painting a different color.

[Doug_B_928]

Thanks, Paul. I'll be sure to ask the paint shop. Re compatibility, the paint shop is a collision shop but they are regarded as the best in the city. They use only Sikkens waterbourne. I spoke with their supply store and the fellow there suggested that, for the parts that I will be painting, I use Matrix because he felt the solvent-based would be better for an at-home job and it is less expensive. I plan to do all of the primer and body work myself. The guy at the supply store said that Matrix epoxy and surface primers would be compatible with the Sikkens paints. Does the Matrix/Sikkens compatibility jibe with any one else's experience here? I've read here that sometimes 'jobbers' say things are compatible but they turn out not to be. I haven't seen data sheets for either line. Do they usually say which other manufacturer's lines they are compatible with?

[Pauld_94S2]

Get a small quantity of the two brands in a color you plan to use and try them out.

That will give you the best answer, and you'll get a little practice spray painting.

[Cairo94507]

Hi Doug - Congratulations on your '73 914. Terrific year to own. It never hurts to plan ahead by selecting the color and paint you wish to use. However, you might consider tackling all of the rust and metal repair/fabrication first. Just use primer to cover your work to keep anything from flash rusting as you continue working around the car. It is pretty common for one's vision of their car to change as they begin working on it. By using primer to protect your work, you are not locking yourself into a given color - of course, if you are going back to original color, not much of an issue. Additionally, have you been on 914World.com? Lots of great advise and build threads there. Best wishes and Cheers. Michael

[Doug_B_928]

Cairo, much to my wife's dismay, I'll be taking it back to its original Raveena Green (never seen it in that color). Yep, 914World is terrific and Jeff's 'Brining out the dead' and Michelo's 'Digging into Hell' are my go-to threads. Just haven't been able to find any info that tells me how to mask edges properly in the scenario I'll be in.

Merry Christmas to all!

[962porsche]

personally i do not like to paint jams 1st i paint them as i paint the out sides of the cars panels .
we will spray the under sides of the hoods and trunk lids 1st then after dry flip them over mask and paint the tops sides .
things like the jams of the doors , hood and trunk lids on the cars body we paint at the same time as we do the painting of the car .
in the end you will have a cleaner job with out masking lines .
things like doors we paint off the car and we do both inner and outside of the doors all at the same time . we hang the doors from the ceiling of the booth oriented the same way they are hung on the car .
we will also do this with many cars that have bolt on fenders painting them off the car but hanging in the booth the same way they are in a car .
we orient them too as they would be on the car this is because of metallic flakes with metallic colors and the need for them to lay down all the same way to get proper color matches .

there are many shops that will want the panels bolted back on the car . they tend to do this because they can't paint things hanging in the air . they worry about damaging panels bolting them back on after they are painted .

[Doug_B_928]

962, so when you do the hood/trunk lid bottoms first, you mask off all of the edges so that you're just doing the bottom, then when you do the top you are also doing the edges, correct?

[962porsche]

let me see if i can explain the steps ???
so on this 69 camaro the new deck lid didn't fit . i had to shave the two corners and weld them back together to get some kind of a gap .
i then did all the body work it needed and prepped the top side for primer using 180 grit . i did the same to the under side around the area ( corners ) were i did my body and metal work. i will not be priming the hole underside as more product is not good .
you should not prime just for priming sake .filler primer is meant to give a sandable substrate to make your body and metal work straight .
so the reason i'm spot priming the underside is the panel has a E-coat primer on it .
in your case you should have a top coated (painted) surface.

after i finish filler priming the hole top side and spot priming the underside i will let the primer dry/cure and then sand the black E coat primer on the underside with a red pad and sand the primered areas with 320 or 400 .
at this time the top is not sanded yet !

i will then blow off the underside from my sanding and wipe every thing down with a prepaint cleaner and tape it off .

the top side is still just in filler primer and not sanded yet .

i will back tape the edges and mask
with the hole lid back taped and masked you would spray a coat of sealer/

going wet on wet from the sealer you would let the sealer flash off as needed then go right to your top coats ( base clear or single stage )

after the underside is dry and cured you then flip the lid over and do the same to the top side .

it's ok to back tape and then if need be depending on how you want to spray you product to spray over the edges and over the product you sprayed before .

in this case with the camaro the trunk lid has a flat edge on both sides making back taping and masking easy .


i should add you should not do any painting until all your body work is finished and the hole panel is in it's final primer .
having to do body work to a panel that had it's under side painted could totally screw up your paint work .

[Doug_B_928]

Terrific, thanks 962!