Photoetch sheet varnished?

[Levent Suberk]

I blackened brass eyebolts and brass wire with gun blue. However when I tried gun blue on photoetched brass sheet it didn't black any. I scratched a little and it seems that there is a clear varnish on phoetched sheet. Is this true that any varnish used on photetched sheet?

Model kit is Artesania Latina RMS Titanic Lifeboat.

 

[Jimsky]

Most likely, yes! It is a solution to keep the PE from oxidizing itself over time. Who knows when the actual freet finds the home. It must be presentable to be sold! You can use 500 grit sandpaper to clean, also use vinegar to dissolve the protection surface.

 

[Levent Suberk]

Thanks Jimsky.

 

[Uwek]

Since a shorter time I use a fiberglass eraser or rubber - it is working extremely well