Formaldehyde, hide glue and the resulting inlay...
John Aniano, in NJ...
>Hello All,
Thanks to all who suggested how to find formaldehyde a few weeks ago. What follows is a story of the final result.
Here is an image image of the violin bow I just finished. It shows the part nearest the player's hand - called the "frog". I glued in two mastodon ivory rings in 13mm recesses drilled into the frog sides. Then, inside the rings are two 11mm wide five-pointed mother-of-pearl (MOP) stars on both sides of the frog. Around each of the stars are five 2mm diameter MOP dots and a final 3mm pearl dot at the center of each star. All were glued in place using scant amount of liquid fish glue. In the spaces between the ivory and pearl pieces, I put a mixture of liquid fish glue (from Kremer Pigments) and a black pigment called atramentum (also from Kremer). Atramentum was a traditional black used to make ink for quill pens. Atramentum is made from an iron compound reacted with oak tree bark. When mixed with fish glue, packed into the voids between the ivory ring and pearls and dried, it makes a nice black/gray color that blends well with the ebony. I filed down the excess dried mixture to make the surface flush to the curved sides of the frog. Finally, I put a small amount of formaldehyde in a baby-food jar, popped it into a small Rubbermaid plastic container and put the inlayed frog into the "fuming chamber", put on the lid and allowed the formaldehyde to do it's thing. Apparently, formaldehyde reacts with the polymer chains in the dried glue and makes them pretty much waterproof. This was my aim, to make an inlayed frog with the materials that were available to 19th-century European craftsmen. It has to be waterproof because the player's hands touch the surface of the frog.
For scale, the whole frog is ~45 mm long and is trimmed in Sterling silver.
John