Car painting question - how to mask and not have a line between old/new paint

[chrisntam]

I'm thinking about painting the inside of my trunk.  My '70 was repainted sometime in the past with basecoat/clearcoat that is currently acceptable.  They got overspray in the trunk area by where the weather strip goes (the inside lip of the trunk area).  Thinking about re-spraying that area only.

I've painted cars in the past - more than 20 years ago, so I have some experience, though I haven't done any repair or touch ups, only complete re-sprays.

Anyone know how to deal with the inevitable "edge" where the new paint under the trunk that will butt up next to the existing paint on the outside of the car?  Is it a masking issue or do I wet sand the edge and knock it down that way?

Any advice would be greatly appreciated.

chris.

[The Tassie Devil(le)]

Can't you just mask up the rubber?   Then paper the rest of the car so no overspray gets there?

Bruce.

[chrisntam]

I'm removing the weatherstripping.  My area of concern is where the "horizontal" part of the body meets the "vertical" edge of the inside of the trunk lip.

Much like if I was painting a door jamb.  I'd be masking the outside of the body, painting the jamb.  When I remove the masking, there should be a line where the new paint (in the jamb) meets the old paint (on the outside of the body).

I'll post a picture in the next day or so, that may better explain my concerns.

Thanks!

chris.

[Dan LeBlanc]

You either have to blend and buff or find a hard seam to conceal.

[55 cadi]

Hello,

If it is just some overspray you are trying to get rid of, there are products that remove the over-spray without changing or damaging the rest.

[Duncan Fox]

Chris , have you ever heard of "back masking"? Its an old timer trick. I have used this to achieve a blend in areas such as you describe. Its a process probably more for an experienced painter though someone who has good gun control. The tape and paper are firstly applied over the surface to be coated and then  rolled back over on itself leaving a shrouded soft sticky edge adjacent to the blend area. Back masking is how we describe it down here, you Yanks may have another term for it. If your colour match is spot on you can achieve a near perfect transition after clear coat.

[Rlamb10769]

This is a product I use when I blend, it leaves a soft edge. This is a 3m product, there are cheaper brands available at your local paint store.

http://3mcollision.com/3m-soft-edge-foam-masking-tape-06297.html

[chrisntam]

Here's a couple of pics of the trunk area...........

Is removing the trunk lid just like taking the hood off?  Don't see any way to paint by the back window without removing the lid............

[Joe Manna]

Depending where you are painting,you can take the tape and fold it outward.you will have some overspray but you can probably buff it out by hand.

[cadillac ken]

I'm assuming you are using a base/clear paint system or at least a urethane single stage.

I have a trick that works pretty well in my shop.  You can mask off the area as you intend (at the inside corner) that will result in the tape line you are worried about.  Do your touch up and remove the tape immediately.  In your case I would recommend using an airbrush (because of the size of the repair "line"), but you can use a small paintbrush.  Use a suitable Blending Reducer that is compatible with your paint system full strength in the airbrush.  Direct the reducer at the tape line and spray it.  Don't worry about it if you get a little too heavy and there are small "sags" caused by this process.  You will see that when the reducer has evaporated it's most times gone.

You can always just try this on a scrap piece of metal to get a feel and a look at what it will do for you before you attempt the actual repair.

I have done this many times and it has worked great.  Being that this is at an inside corner you should get a great result. It takes a little skill but you said you have painted before so you should be fine.  If there is a little "line" left after the area is cured out, you can usually hand rub that out.  Just wait a good week or two to do the buffing out by hand part.  You want that new material to be cured to get the best results.

Good Luck!

[Foxhound1]

Just a suggestion.  Seems to work for pretty well for those folks I have talked to.

https://www.tubetape.works/

[Eric DeVirgilis CLC# 8621]

It will take a real artist to accomplish in such a way the paintwork will not be detectable, either visually or by touch.

Wherever possible, I try to take the path of lest resistance. Before breaking out the spray guns, paints, tapes and reducers - it might be worth taking a little compound, followed by hand glaze and some wax to the offending areas and see how it turns out first. It's a heck of a lot cheaper and the results may surprise you with little to lose if it doesn't pan out.

Just a thought.

[Jon S]

It will take a real artist to accomplish in such a way the paintwork will not be detectable, either visually or by touch.

Wherever possible, I try to take the path of lest resistance. Before breaking out the spray guns, paints, tapes and reducers - it might be worth taking a little compound, followed by hand glaze and some wax to the offending areas and see how it turns out first. It's a heck of a lot cheaper and the results may surprise you with little to lose if it doesn't pan out.

Just a thought.

My thoughts also, except use 3M Hand Glaze instead of the compound.  Great results and doesn't cut through like compound would.

[Mike Josephic CLC #3877]

Chris , have you ever heard of "back masking"? Its an old timer trick. I have used this to achieve a blend in areas such as you describe. Its a process probably more for an experienced painter though someone who has good gun control. The tape and paper are firstly applied over the surface to be coated and then  rolled back over on itself leaving a shrouded soft sticky edge adjacent to the blend area. Back masking is how we describe it down here, you Yanks may have another term for it. If your colour match is spot on you can achieve a near perfect transition after clear coat.

I agree with Duncan.  "Back Masking" is the way to go -- I've used this technique for years
for touch up work and I'm no paint expert by any stretch.  It takes a little practice, but what
this technique avoids is leaving a "hard edge or line" between the old and new paint.

Your color match has to be pretty good and if it is, a little buffing and you will never see
the transition area.

Mike