:: The Incorporation of Madder Lake in an Oil Varnish ::

Madder lake, or a pigment made from a similar vegetable product, may be incorporated into an oil varnish by one of two main methods.

The first system involves using the pigment in the form of a 'glaze' over which the varnish is eventually applied, and the second method is to incorporate the pigment into the varnish in the form of a suspension of fine particles.

The use of any pigment compromises the transparency to a greater or lesser extent, and I suggest that the application of pigment to a varnish be regarded essentially as 'modifying' the colour of an already self-coloured varnish, rather than as a basis for the colour itself.

Madder as a Glaze

As a basis for this process, I use the excellent madder lake produced by the recipe of David and Nest Rubio, but I follow their final grinding process only down to the pestle and mortar stage.

To incorporate the lake with linseed oil, every last trace of 'grittiness' needs to be ground out and that I found almost impossible to achieve with a muller alone.

I overcame the problem by using a ball mill (barrelling machine) which I bought for about £40 from
H S Walsh and Sons Ltd,
1 - 2 Warstone Mews,
Warstone Lane,
Birmingham B18 6JB,
Telephone 0121 236 9346,
who I understand will also supply by mail order.

I found the following technique gave good results.

1. Grind the madder lake as finely as possible with a pestle and mortar, and put about 1 - 2 teaspoons into the barrelling container.
2. Add about 8 small roughly spherical stones, together with about 50 ml of industrial methylated spirits (ethanol).
3. Barrel the mixture for 2 - 3 days.
4. Remove the stones, and replace the screwed-on cap of the barrelling container with a loose-fitting lid of aluminium foil.
5. Place the barrelling container in a warm place for the alcohol to evaporate.

The dried madder lake only requires about 30 seconds light mulling in linseed oil to produce a grit-free glaze.

Regarding the application of the glaze to the instrument, I have found the traditional way of laying it on with the hand extremely wasteful, and I have achieved satisfactory results with a stencil brush.

Madder in the Varnish

Madder lake may be incorporated into a self-coloured varnish by the following technique.

1. Pour about 100 ml of oil varnish into the barrelling container, add the stones, and about 1 - 2 teaspoons of finely ground madder.
2. Barrel for 2 - 3 days.
3. Remove the stones, and allow the varnish to rest undisturbed for 24 hours to allow the heavier particles of madder to sink to the bottom.
4. Decant the varnish into a fresh container without disturbing the excess pigment in the bottom.

The decanted varnish will be the varnish you will use.

Note that the madder will continue to precipitate from the decanted varnish, so its important to barrel for about 15 minutes between coats.

If you feel that the varnish still has too much pigment (ie its faintly opaque and tends to be dull) leave it for another 12 hours, and decant again.

Telephone: 01902 755610 & 07976 245861
E-mail: anthony@perryviolins.co.uk

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