updated (12/28/2008)

... Once you have decided that you need to adjust the plate frequencies, you have mainly three methods open to you: ..(1) Apply a new ground coat (made to increase the plate frequencies) and then re-varnish the instrument. ..(2) Re-graduate the plates from the outside. ..(3) Open up the instrument (by removing only the top plate) and re-graduating the plates from the inside.

Method # 1: Apply a new ground coat and revarnish...

...This method might be chosen if you would rather re-varnish than take off the top of the instrument and regraduate (adjust the plate tap tones) from inside. Since a proper ground coat may well raise the frequency 80HZ immediately and increase the amount of frequency increase due to sunlight, this method can easily raise the plate frequency by 160HZ or so. So if a large increase in plate tone is needed, then this method should be considered. ... { Please see elsewhere my articles on removing varnish and also ground recipies.}

...Once the varnish is removed from the exterior of the violin, the surface should be carefully sanded in increasingly fine grades always sanding down grain (down hill) and in the direction of the grain. This will really bring out the beauty of the wood grain on re-finishing making an eye catching appearance (even from across the room!)

...When the wood surface is ready, the ground coat(s) are brushed on and allowed to dry. The varnish coats are then applied in the usual manner. When fully varnished, begin exposing the violin to sunlight, as described above, until your goal frequencies are achieved. When the varnish has dried for several months, it can be surface sanded (say with # 280 sandpaper and then finer and finer grades (until # 12,000) and then polished with linseed oil and rottenstone using a felt pad for a fine luster.

...This method can be used under special circumstances to adjust plate frequencies, but it has several disadvantages and advantages: ...First the advantages: The body does not have to be opened (with its' attendant problems). Since the plates are together, it might be easier to hear the relationship of the top and back plates as the tap tones are adjusted. ...Secondly some of the problems: The varnish must normally be removed down to bare wood (this can be a bit of work and then there is the revarnishing when done). Any U.V. effects on the wood surface and ground layer effects will be removed, so their eventual effect on plate tone must be estimated when graduating the bare wood plate; so that when the new ground coat (first varnish layer, if any), and subsequent varnish layers, and sunlight exposure effects are complete, the tap tone will be where we want it to be. Since regraduating involves removing wood to regulate tap tones, rather than shaping the surface for a pleasing appearance, surface irregularities may easly result which will be visible when varnished. ...The wood shaping techniques necessary are the same as described in the choice # 4 section below. ...For these reasons, it really is best to leave the exterior surfaces intact and do regraduating (wood removal on the inside plate surfaces inorder to adjust the tap tones of the plates) with the instrument opened.