Home - Varnishing - Grounds

Plaster of Paris ground



Plaster of Paris is produced by the grinding of gypsum and subsequent heating to 150C to get rid of water. For this recipe, any plaster without additives {resins} can be used.

The recipe:

  1. Put a measure of plaster in a pot. Keep adding water, while vigorously stirring, until you get a milky solution. The large amount of water will prevent the gypsum from setting.
  2. Keep stirring for about an hour.
  3. Stir /or shake/ every other hour for a whole day.
  4. Stir /or shake/ once a day for a whole week.
  5. If necessary, add more water so that it stays withing the consistency of, somewhat creamy, milk.

You have now prepared the ground solution. The remaining plaster can be left in the jar or allowed to dry to be used on the next instrument. If left dry, just add some water before using it again.

Application:

  1. Put the milk first on the back of the violin, using a brush.
  2. Before it sets, wipe off with a towel trying to remove as much as possible rubbing it at the same time into the pores. Great care should be taken especially with the edges of the plates and the areas of the scroll where most of the end grain is.
  3. Let it dry. Don`t be alarmed at the plaster-like looks of the instrument at this point.
  4. Take your colorless oil varnish. It should be of the viscosity of honey. Apply a patch of this varnish, the size of a quarter of the plate, with your brush, on the back plate. Right away, wipe off all the excessive varnish with a cloth so that a silky smooth surface of the color of honey remains. Move onto the next section.
  5. When you are finished with the back plate, you can expose the new ground to UV for about ten minutes to harden it. Or if you have a varnishing cradle, just continue on the front plate.
  6. Continue to the front panel, then ribs, then the pegbox and scroll. Work in small sections so that you can wipe off the varnish before it sets.
  7. If necessary, apply to difficult end grain parts more gypsum and wipe off again, repeating the whole process {including varnishing} where needed. The whole surface of the instrument must be sealed having that silky sheen.
  8. Put in your UV box or out in the sun and let dry thoroughly.

Special thanks to the Roger Hargrave for the recipe and application.
If this is your first violin just get regular linseed oil and you`ll be fine. Washing: Filtering the oil and cleansing the mucilage and particulates from it, washing it with water. The result is a much clearer oil with many added benefits: the oil dries faster, has greater gloss, works better with impasto techniques, has excellent color depth, and is more viscous than chemically refined oil. Linseed oil, as commonly sold for artist use, is processed using high temperatures, chemicals, and solvents. The resulting oil has very little of the fatty acid content that is essential for the oil to dry. This is why linseed oil has the reputation of drying so slowly. These chemical refining processes are fast, but leave the artist with a less-than-ideal oil. Interestingly, throughout much of history artists have been aware of the need to “clean” their linseed oil. For example, in the 16th century friends of the artist Perugino taught how to clean oil by putting it in a horn-shaped glass with an opening and a stopper at the bottom. Water was added and the mixture was stirred. After the water settled, it was drained from the bottom and fresh water was added. The process was then repeated seven or eight times. The painters referred to the resulting oil as “purified”. Today, because of the availability of large scale chemical refining, most artists have never even heard of this process. - 2022-02-26 15:22:51
Where do I get washed linseed oil - 2022-02-20 20:08:13
Thanks for laying that out - 2022-01-29 16:42:34
I am wondering, and I would ve happy if you can confirm- the washed linseed oil we are talking about is only washed, not cooked? - 2021-11-12 21:15:09
The only ground coat I use is washed linseed oil. I take a clean t-shirt and apply a thin layer of the oil. I then put the violin into my UV light box for 10 days. I repeat this process one more time. Nothing looks better on wood than oil. - 2020-05-26 00:57:40