ORCA Lampshades: Test

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Understand, that even with all that information, restoration is not easy. Shellac is an organic product, which, unlike modern chemical shellacs, will darken and warm tonally as it ages. True shellac is created from the lac bug, and so, from one batch to the next, all technically the same inherent resin tone and from the same region, there are variations from season to season, due to the ingestion of various plants.  “Shellac” products from local hardware stores are generally not created from the lac bug, but synthetics, and will produce none of the organic properties (darkening over time and variations) nor the warmth of true shellac.

We tested for shellac versus oil, and to find the proper color dyes.

 

TEST: SHELLAC VERSUS OIL

On a sample of lesser weight Kochi Mashi provided to us by Hiromi, we tested the Smokey Maple glaze (oil paint) against a shellac finish (color did not matter) to feel the difference in the oil paint versus shellac.  We want a proper balance in strength and flexibility, with no cracking.

The shellac appeared to provide more strength to the paper, though it made it a bit more brittle.  Oil caused the paper to be flexible but a bit mushy, and not as strong standing up.

What is needed is strength with enough flexibility that the paper does not crack.  To this end, we are choosing shellac finish, which is also supported in many historical lampshades from this time period.

Our goal now is to find the proper color, and only use as much shellac as needed in the proper cut to allow for strength without causing cracking due to too much shellac.

TEST: SHELLAC COLOR + BUILDUP

 

MPFC created a 1-lb cut of superblonde shellac using lab grade isopropyl alcohol.  It is imperative that the freshest lac flakes be used when creating shellac.

Shellac is not toxic, but the Transtint dyes are toxic, which is why a mask is worn when using them.

Various shades were tested on boards and compared with original pieces of lampshades, right, to find the correct color for the paper.  This is not science but art, as one has to be able to judge how the color will change as it is built up on the paper.

After we eliminated many possibilities, a full test of color buildup on paper was created using the finalist dyes.  It was only then we came to the final color.

FINAL CHOICE

Transtint #6004 “Medium Brown” was chosen; 2-4 drops was slowly dropped one drop at a time then mixed in 1 3/4 cup of shellac (we decant shellac in glass canning jars) to create the proper shade.

This is not science but art: we found the organic superblonde shellac could be lighter or darker even when we mixed the same formula.  This is due to disparate resin concentrations from one species/batch of lac the next, largely due to dietary considerations.

Note: Handmade paper, too, is not predictable precisely because it is handmade,
and so the colors from one batch to the next changed slightly.  Even the exact same leather lacing used in the first and subsequent shades had changed slightly in the dye lot.

    

Other tests were performed in a small buildup:

  • To see if we needed an undercover of plastic/paper/or nothing to keep the pieces from sticking to the tabletop, especially in the first coat (it was deemed necessary);
  • Various forms of graphite or other pigments sticks were sampled to add the aged distressing (we chose two colored sticks);
  • How these powders adhered to the paper, and problem solving that issue;
  • Shellac and/or wax was experimented with as fixative coats.

Testing was completed, and a protocol was in place for three test shades; we will run through the chosen protocol, then move forward to address the final.


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