Thursday, September 8, 2011

Grand Piano Restoration: Cabinet Finishes

In years past I used to do a variety of finishes that were popular; varnish, shellac, linseed oil French polish, or Danish oil finishes, bees wax and other finishing waxes, nitro-cellulose lacquer and catalyzed lacquer.

Some of these finishes, while popular during certain periods of history, are not very durable; the oil and wax finishes in particular leave the grain open a considerable amount, and this allows contaminants into the wood damaging the veneers and the look of the cabinet. Shellac under certain conditions can be delicate also, especially if applied incorrectly.

French polishing takes considerable time, which makes this one a considerably more expensive proposition; done only on request by the piano owner.

One type of finishing not tried here is the polyester finishes for pianos. Most of the pianos I work on here are vintage or period pieces, and are not served well with a modern finish such as this one. For the most part, this type of finish became popular in the late 70’s and early 80’s. While it is quite durable polyester finishes are usually high gloss. Along with the high gloss is the fact that black has become quite a popular colour for pianos. The result is after a few years the high gloss finish develops many small scratches, wear lines, and fingerprints which are magnified by the black colour. This gives the finish and old and tired look.

For cost effectiveness to both the owner and the restorer, lacquer is the best for finishing. Over the years I have tried several types of lacquer, and have come to the conclusion that nitrocellulose is best. 

Nitrocellulose was first introduced to the market in production furniture around 1900, and by the 1930’s most of the pianos and furniture manufactured was being finished with this product.

With the inclusion of vinyl polymers and catalysts found in lacquers today, one of the characteristics of catalyzed lacquer products when dry, is that they become quite brittle and chip easily, requiring touch-up. As pianos have lots of edges, using this type of furniture grade lacquer is not good. These types of lacquers cannot be touched up or sprayed over top with good results once the catalyst has set for more than 30 days. 

With nitrocellulose, one can touch up or spray a new coat or re-start the lacquering process at any time in the life of the finish. The nitrocellulose with 35% sheen I find to be the best one for vintage projects; 35% sheen gives you a little shine and assists in hiding permanent un- repairable damage to the casework.  I have used lacquer with less sheen, down to 10% at times for certain jobs, with good results. 

A sheen of 35% or less shows the beauty of the wood instead of the shine of the finish.

When using high gloss finishes, every little bump and divot in the cabinet will show. With vintage instruments this is not the desired result.

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