Equipment

1. Hot plate preferably thermostatically controlled, with diffuser screen.
2. Thermometer. (maximum of 350° C will suffice). A candy thermometer or a cheap Radio Shack multimeter with a thermometric probe.
3. An enameled or stainless steel pot.
4. Lab spoon or glass rod for stirring.
5. Scales.
6. Coffee filters.
7. Fire extinguisher. (ready at all times)

Ingredients

1. 200gr - Larch Resin, Burgundy rosin, pitch of pine/Venetian Turpentine or Burgundy rosin alone.
2. Linseed oil or Walnut oil Cold pressed.
3. 200gr liquid wood ash.
4. 1/4 teaspoon - Slaked Lime.
5. 1/2 teaspoon - Manganese Brown/Umber.
6. Spirits of Gum Turpentine.

Ingredients preparation

Liquid wood ash

1. Burn preferably hard woods, a mixture of spruce and maple shavings is acceptable.
2. Put an amount of ash that is equal of that of resin {200gr} in a coffee filter.
3. Pour an equal amount of distilled water {200gr} thru the filter filled with ashes.

Resin

Various resins can be used: Larch Resin, Burgundy rosin, pitch of pine/Venetian Turpentine or Burgundy rosin alone.

All cooking is done in an enameled saucepan or in a stainless steel pot on hot plate, preferably with a screen diffuser. Do not use aluminium dishes as they may burn thru.

1. Add 200gr liquid wood ash.
2. Add 1/4 teaspoon of Slaked Lime.
3. Add 1/2 teaspoon of Manganese Brown (Umber)
4. Add 200gr resin

Cook at 250-300 C for 5-15 hours. Longer cooking times yield darker color and shorter drying times. Pour the hot resin on an aluminium foil and allow it to cool. Crush, measure and you have got your resin.

Cooking with iron present gives a redder color. Without iron gets you green/yellow/brown color.


Preparation

Oil Varnish 2 parts resin to 1 part oil - 56 percent of resin equals 100 percent of oil.

1. Heat up the measured resin.
2. Slowly add the Linseed oil. 1/2 the volume of the crushed resin.
3. Bring temperature to 300 C.
4. Stop stirring pot when the varnish starts to string-you want any sediment to settle to the bottom of the pot. Test the varnish periodically by conducting the string test *.
5. Cool the varnish to 200 C.
6. Heat spirits of gum turpentine in the same quantity as the resin and add to the varnish when the cooking process is completed. Observe care in warming the turps, it is warm enough when a little vapor is observed forming above the turpentine in the cooking vessel.
7. Pour warm mixture through a cloth (old t-shirt) to filter out any undissolved particles or dirt. Decant just the clean varnish, avoid filtering the sediment from the pot.
8. After varnish has completely cooled you may add a tablespoon of alcohol or 1/2 tablespoon of alcohol and 1/2 of lavender oil. This last step will help the varnish dry it also improves flow out and helps dissolve any undissolved particles.

Characteristics

This varnish does not skim over in the jar and will improve with age. Do not apply this varnish in a thick film, always spread it thinly. Working time on the surface is 20-25 min.

Usage

You should add a few drops of thickened linseed oil to the last layers of varnish to maintain the fat over lean rule of oil painting.

Drying: The varnish will dry overnight. You can optionally use UV lighting in a drying cabinet.

Polishing: When you are ready to rub down and polish the surface this varnish will soften with alcohol. You can rub down and polish by putting some xxxx pumice on a cloth with oil and alcohol just as you would when doing normal French polish. For a final polish I use the same technique with a bit of tripoli instead of pumice. I use linseed oil when French polishing-this facilitates an additional coat of varnish (I don't have to worry about having a non drying oil on the surface).

Category: Varnishing