OldTools Archive

Recent Bios FAQ

269306 Erik Levin 2019‑10‑10 Heat tolerance of shellac and varnish finishes
Another round of "can I save it" on an instrument case. A pre-war Starrett 224C
case (the tool came complete, but in need of work, and the spindle and anvils
are not lapped in mirror finish and square, by hand) that has mechanical damage
and mold. It was rid' hard and put away wet, literally, including every screw
hole for the hinges being stripped (some 'repaired' by stuffing with steel wool)
and an assortment of glues to hold it together.


The wood is raised panels of oak, with softwood, box jointed, sides. The
original finish was a varnish of some type.


The original finish was a varnish (denatured alcohol turns it white), and there
has been repair done with shellac (softens/dissolves in alcohol). My preference
is to not remove more finish than I need to, as the exterior of most pieces is
in surprisingly good condition. I would like to preserve the original labels and
decal. To kill the mold, I plan to heat to 60C (140F) and hold for 30min. This
should be sufficient to destroy any live organism and kill any spores.


Any experience with heat at these temperatures on varnish of the era and/or
shellac? Would I be better off to just remove what I can before heating?


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Recent Bios FAQ