Resuming a Painting Model That Has Been Sitting for a Few Days. Do I need to Sand My Base Coat?

[TheCamaroKid]

So I've been painting a 66 Pontiac GTO with Tamiya Pearl White. As my mold was starting to get good coverage, I ran out of paint. Further bad news no one has Tamiya Pearl White for plastics save for one seller on eBay. No one locally had it. So I ordered it but it likely won't be here until the middle of next week. In that time, my car will have sat for over 5 days. I'm assuming this means the paint will have harden.

What is the best step for resuming painting? Should I sand what's on that with fine sandpaper (2000-3000) grit like I would for a clear coat and resume painting?

[Bainford]

Good question. Solvent-based paints have a time-zone during which new coats of paint should not be applied. New coats have to be applied within a specified time from the first coat, or wait the curing period before applying a new coat. This will differ from one manufacturer to the next. Tamiya should post the recoating times on their site, or spray cans sometimes have this information on them. It will say something like; recoat within 6 hrs or wait 48 hrs (those times are representative, not actual times). Make sure your are well past the wait time before applying the second coat. It would be helpful to know what those times are Tamiya lacquers, but I'm guessing plenty of time will have passed when your new paint arrives. Many builders ignore these time limits without issue, though I have also seen many examples of paint problems on this site that were caused by recoating too soon (usually manifesting as pin holes or micro-canyons in the paint surface).

I would colour sand the paint, if for no other reason than to speed up the gassing out and curing of the paint. If you have a dehydrator for drying paint, put the body in there for a couple days after colour sanding. When the new paint arrives, start your paint process from scratch (mist coats, then wet coat coat, etc., whatever your process is). Some will say this is all being overly cautious, but there is nothing wrong with heading manufacturers recommendations. Besides, you have the time. One of the site paint gurus (and, to be sure, I am not one) may come along with some better advice, but that's how I would handle it.

[Ace-Garageguy]

Lacquer is generally not recoat-window time-sensitive. You can recoat it at any time...usually. But if I'm going to shoot over lacquer that's been sitting for a while, I'll scrub it with Comet or Soft Scrub and a toothbrush to give it a little tooth. I'll also final-wipe it with 70% isopropyl alcohol, because believe it or not, fisheye-causing contaminants can get on the surface of a model in just a few days. 70% iso will clean them off without harming the paint.

Sadly, some products labeled "lacquer" behave like enamels when recoated even years later. I discovered this when I tried to shoot Duplicolor black lacquer over old Ace Hardware-store black "lacquer", only to have the old stuff (that had been on the model for almost 10 years) crack and wrinkle.

I rarely use enamels, and would most likely strip an old enamel job simply because there's always a chance solvents in the new paint will attack and wrinkle the old paint.

[restoman]

Like Ace said above.

The only sanding I would do is to possibly de-nub any dust specks.