Washing and Body Fillers

[Roger U]

It's been a long time (in the 1960s) since I've built a model. Back then I didn't even think about washing the kit pieces before building the model. And, I didn't use body fillers.

Now I plan to start building again and am wondering is it best to wash and sand the body, and other pieces, before or after applying the filler?

[gman]

Yes, washing the model and cleaning off any mold release or oils is a good start.

Depending on what filler you are going to use, rough sanding the area to be puttied will give the filler some tooth and allow it to stick. When sanding your filler, you use progressively finer grits to feather out the area, and that will take care of the rough scratches made before the filler. Prime the area, sand some more, and soon you'll be ready for paint.

[Brutalform]

After any work, like removing sink marks, removing flash, and getting everything corrected, I always wash the parts in a bit of Dawn and warm water with a toothbrush to get it ready for primer. Filler is not always needed. Some kits might only need minimal cleanup, but others may need some additional body work. For me, after priming, is a perfect time to check my work. And when it’s wet, this allows me to see if the body looks smooth enough, or if it needs additional attention. Anything not corrected in the early stages, will not be hidden by paint. 

Edited April 8, 2020 by Brutalform

[Mark]

Clean the parts before doing any sanding, otherwise you are grinding mold release into the sanded plastic.