Proper Way to Add Trim Color

I have a couple of questions for the paint gurus. When adding a trim color, I assume that most paint shops simply paint the base color and then add the trim color on top of that. That leaves an edge, especially if you're using a thick paint like the polyurethanes. Does it make sense for a DIY painter to butt these two edges together? I know it's more work, but does it turn out any better.

Secondly, if I overlap the paint, can I wet sand the joint before clearcoating? Or should I clearcoat and then buff the edge? What's the best way to handle this. Thanks.

trim color

I don't know much about painting but on cars if you pull the tape before the
trim color dries the paint will flow some to the transition and smooth out
the line , some paints need sanded before clear 2000 grit should be fine for
that, and wet sand the clear 4000 or 6000 grit for the glass smooth
surface.. or something like that


Danny..

An example of Danny's reply can be seen in an episode of "From the Ground Up" When the builder paints 2 red stripes on a white panel. He pulls the tape from one before it drys while letting the other dry completely to show the smooth and abrupt transition lines.

Steve

If you're using a base/clear paint, the color coats will be very thin and should leave very little edge. Sanding the color coats is not a real great idea as it can cause the color to lighten and will totally screw up a pearl or metalic. One tip I can offer is that after masking for the trim stripe, before you shoot the stripe, spray a light coat of the background color or an intercoat clear. This will seal the edges of the tape and prevent the trim color from bleeding under the tape, giving a nice crisp line.

Steve Zicree
RV4 last 90%

Trim color

Do NOT use masking tape for color. Use a good 3M tape. They make them is different sizes (1/8-1/4-3/8-1/2") I used 1/4 tape to mask off my trim lines and then used making tape to cover the 1/4 tape with masking paper. Once everything is masked off real well, sand the trim area with Grey Scotchbrite. Make sure you get right up against the trim line on the base color. Once you've painted the trim color wait about 4 hrs after spraying and pull the trim tape (pull towards you with the tape leaving the surface at over 90 degree to prevent pulling up any base coat paint). Be very careful not to touch the trim paint. You can use a new razor blade to scrape away any bleed through under rivet heads and skin lap joints. It will leave a very crisp edge that won't stick up that much to make 1/100th of 1mph difference on your airplane.

There's several options depending on the system you're using (Single Stage or Two Stage), but the classiest way to do multiple colors is to go with the Two Stage system using base and clear coats.

Base coats can be taped after very short drying times so what you would do is to spray the base color, then lay out and spray the stripe colors (still using base coat). You should be able to do the whole process in a day easily.

Then with all the base colors on, take off every bit of stripe tape and clear coat the whole thing. The clear will smooth out the color transition areas.
Do NOT under any circumstance do any sanding of the base coats during the process. Clean the base coats with a wax and grease remover (such as PPG DX330) and wipe dry with clean towels, and then use a tack cloth to pick up any dust. But do NOT sand any of the base coats before clear coating.

The fewer number of colors you use, the easier this is. If you like fogging and ribbons and all that stuff, the same applies. Do all the color with the base coats and clear it all together.
If you're a newbie to this sort of stuff, it's possible that you'll build up a bit of dry overspray while doing the base coats, but don't sand it off before clearing. If you aren't happy with the result (textured finish due to overspray under the clear), you'll want to let the finish dry, lightly wet sand with something like 1200 grit sandpaper, then clear it again (make sure you don't sand through the original clear).
Now's the time to rethink that super custom, multi color, ribboned, checkered, color scheme

Also remember that the more colors you use, the more tedius it will be to repair those areas later when you get an ouchy that you can't live with.

Great post Vern. Thanks.