MITRA Forum Question Details

​We will be getting to the particulars soon on your query but first what is your purpose for sealing the gold? You likely have a very good one but for us to be able to provide helpful info here it is good to understand your reasoning. ANY coating applied over gilding will "rob" the surface of its treasured lustre....but perhaps this is what you are going for?

​Well to be frank gold is always at "risk" I suppose. How important is preserving the current appearance of the gold to you? There are NO coatings that will make the gold appear "the same" after application...Honestly, any of the traditional recipes that call for the occasional use of coatings (for gilding) are intended for manipulating the final appearance of the gold (e.g. matting and/or imparting a particular color). Shellac will certainly work as long as the ethanol within the shellac solution does not bite into the mordant. We have not tested L&B's 12 hr mordant for ethanol sensitivity....yet another consideration is how LONG to wait before varnishing the gold. We will attempt to also reach out to our contact at L&B to see if we can gather more info on their recommendation.

​The short answer will be to seal the oil sized gold layer with clear shellac. Please note that 12 hr size dries very, very slowly, allowing a few weeks after the gilding to dry is recommended. If the gold color seems a bit light the final shellac layer can be tinted with Dragons Blood and or Gamboge, and before the final patina finish is applied. Then the  choice of applying either an oil (Japan) or water based (Casein) patina over the shellac layer. There are always questions; Did the gilder prepare their own shellac or is it store bought, if they prepared their own it is recommended that they cut with additional alcohol as that shellac is stronger than store bought.

Martin Kotler

Frame Conservator. Smithsonian American Art Museum

Thanks Martin

I would add that if you are working on artwork, I would suggest using more lightfast alcohol soluble dyes rather than the traditional gamboge and dragon’s blood resins as those are quite fugitive to light.