How do you stop sanded-off molded-in detail resurfacing after paint?

[OldNYJim]

Excuse the long title but I couldn't think how to shorten it and have it still make sense

I spent the day sanding louvres off the hood of a 32 that I'm building but I'm bit worried about them ghosting back through the plastic once I paint it.  I'll be using Tamiya primer and some kind of automotive lacquer with clear over the top.

Any suggestions to make sure they dont reappear as soon as I lay the last coat of paint down? 

Edited April 3, 2017 by CabDriver
typo

[Can-Con]

After bodywork and priming I always apply a coat of BIN Zinzer shellac. Wet sand it out with 1000 grit or finer and I'm good to go. Never had a problem in over 30 years of doing this.

BTW, It's quite pebbly from the spraycan so I airbrush it thinned with rubbing alcohol. The Alcohol also is excellent for clean up afterword. 

[935k3]

After bodywork and priming I always apply a coat of BIN Zinzer shellac. Wet sand it out with 1000 grit or finer and I'm good to go. Never had a problem in over 30 years of doing this.

BTW, It's quite pebbly from the spraycan so I airbrush it thinned with rubbing alcohol. The Alcohol also is excellent for clean up afterword. 

I will second that. BIN gives you a very stable surface for all other paints. It also seals puttied areas better than regular primers. It is far better to airbrush it.

[Ace-Garageguy]

One method that's always worked for me...assuming you don't have other details on a panel you don't want to drown in primer...after removing molded-on detail, I'll shoot the panel with a relatively hot primer like Duplicolor. The first couple of coats will swell the old detail areas, and the ghosting will be very obvious. Sand it flat and reprime, as many times as is necessary to kill it.

The hood peak has been removed on the Revell '50 Olds hood shown below.

Once it stops ghosting through the primer, it won't ghost through paint. Here's the proof (even though this part was shot with hot Duplicolor green, and cleared with Testors lacquer).

 

 

[Snake45]

One method that's always worked for me...assuming you don't have other details on a panel you don't want to drown in primer...after removing molded-on detail, I'll shoot the panel with a relatively hot primer like Duplicolor. The first couple of coats will swell the old detail areas, and the ghosting will be very obvious. Sand it flat and reprime, as many times as is necessary to kill it.

The hood peak has been removed on the Revell '50 Olds hood shown below.

 

Once it stops ghosting through the primer, it won't ghost through paint. Here's the proof (even though this part was shot with hot Duplicolor green, and cleared with Testors lacquer).

 

 

 

That 's always worked for me, too.

[OldNYJim]

Interesting!  Thanks for the replies guys! 

I wonder what causes this - something with the solvents in the paint, presumably, but why to they bring that detail back up through a previously smooth surface?

 

[crazyjim]

I've coated the sanded area with Tenax7 or equivalent and then sanded some more.  Sometimes a coat of Future floor wax before primer (Duplicolor).

[Snake45]

Interesting!  Thanks for the replies guys! 

I wonder what causes this - something with the solvents in the paint, presumably, but why to they bring that detail back up through a previously smooth surface?

 

Because the "skin" of the plastic is harder than the "core," kind of like case-hardened steel. Sand off a detail and you expose the softer core.

[OldNYJim]

Because the "skin" of the plastic is harder than the "core," kind of like case-hardened steel. Sand off a detail and you expose the softer core.

Ahhh, that figures!

[62rebel]

I'll brush liquid cement over the area and sand it again after the surface dries. same principle as tenax or hot primer. sometimes I'll need to skim coat a little filler over the area as well, then brush THAT with liquid cement and sand after it dries. many many ways to defur felines.