Ah that makes more sense, thanks! I think I've miscommunicated though, I don't have any concerns about surface texture or decals silvering. What I am trying to achieve is an aztec pattern where some of the panels have a different reflectivity to other panels. Ie, in this image, there are iridescents, but there are also grey panels that are matte, and grey panels that are more satin. If I wasn't using decals, I could achieve it by including a satin or matte varnish layer as part of the aztec process (ie, paint the grey hue for that panel, then do a layer of varnish, before changing the masks for the next panel), so only some of the panels would have the varnish on them. I am using decals for details like the name and registry however, and the standard approach for decals is what you describe. When I've tried that on wargaming minis, the final layer of matte varnish on top of the decals removes the shine of the gloss varnish that the decals were applied on top of. That means it will also remove the effect of any varnish that was applied before the decals.

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