decals over decals?

I doubt it... the decal surface is usually pretty slick so the likelihood of any air bubbles forming is pretty slim.

I've done this a few times and never had any trouble.  But silvering can happen when you don't expect it. So I guess it depends how crucial the application is... if you want less risk do the gloss coat.

I looked at the decal surface in the sunlight and it looks to be quite dull, weather it is "rough" or not I can't tell really so I went ahead and brushed a coat of future over it all to helpsmooth it out.

I usually also used future as a "bedding agent" for decals if I am in doubt......stay tuned for the result!

Theuns

When I build any of my Star Trek models that required the Aztec wallpaper decals, I always put on a glosscoat (Testors) over the first layer of decals, then apply the next set.  I would recommend doing a glosscoat layer between the decals, but that's just me. :)

Most of the decal over decal work I have done is small stuff, usually national insignias where they come in layers, such as the Luftwaffe cross & swastika, RAF roundels, Soviet red stars or US cockades that require the red centers or bars portions to be applied separately over the white background piece. I have never gloss coated to seal the lower decal and have never had any silvering issues. Just the usual decal set and solvent where needed...

I completed the decal work on the Fokker D-8.

I used future as a bedding agent for the smaller decals and they look OK,the larger band that goes over the fuse I did not use future but Tamiya markfit as bedding. I hope there will not be silvering on that one's edges.....only the final matt coat will tell.

I have applied a few coats of micro sol so I hope it will be OK.

Theuns

If you want an example of the decal over decal, here you go.  Granted, these are decals done over an Aztec wallpaper.  No harm in spraying on overcoat, if nothing else if you had to strip the decal off, less owrry of damaging the first decal layer.

that is very impressive!

Theuns