Volume 8, Number 2, May 1986, pp.6-8

Formulae for Conservators

In conservation, as in most things, it's not what you use, but how you use it. It is also true that what you use can make things much easier. I have compiled some formulations for varnishes and other handy things. If there is continued interest, I think this might be a valuable on-going Newsletter topic.

The following varnish formulations are attributed to Los Angeles County Museum of Art. Where they first originated is not clear, but very similar recipes are found in painting conservation studios everywhere.

B-72 LACMA Formulation:

8% B-72 in toluene, cellosolve added to retard drying.

A good spray varnish. Cellosolve presents a real health risk, the following is the replacement formulation.

500 ml B-72 50% stock solution
2300 ml Toluene
328 ml Cellosolve

B-72 Brushing (LACMA):

15% B-72 in DEB

Slow evaporation rate of DEB makes for a very good brush varnish. Not the best stuff to breathe, very pungent odor, and quite persistent. Often there is a problem with reticulation if applied over another varnish layer.

3 parts B-72 50% stock solution
7 parts Diethylbenzene

8% B-67 (LACMA):

Good for spraying or brushing. For brushing, it may be thickened by adding a bit more stock solution.

500 ml B-67 45% stock solution
2600 ml Naphtha

The following has been submitted by Chris Stavroudis, Thompson Conservation Associates, Inc.

Beva Cerex (double sided):

Very good for Beva facings, light weight patches, and anywhere you might use Beva film.

Beva 371 1:1 in naphtha is rolled onto silicone coated mylar. When the Beva is dry, Cerex is lightly stretched over the surface and rolled with one coat of Beva in naphtha (a second coat will cause severe wrinkling). Applying the Beva in a "Union Jack" pattern allows any wrinkles to be worked to the edges. It is best to leave the Beva Cerex stuck to the mylar until ready to use.

Beva Cerex (single sided):

Beva 371 1:1 in naphtha is rolled onto silicone coated mylar. When the Beva is dry, Cerex is lightly stretched over the surface (sound familiar?) The Cerex is attached to the mylar by tamping with a naphtha dampened brush. The goal is to swell the Beva slightly, and press the Cerex into the film.

Surface Cleaning Emulsion:

Naphtha:Water:Triton X-100 emulsion (90:9.5:0.5):

Because it is non-aqueous, the emulsion is often milder than spit for surface cleaning. It should be rinsed with naphtha or water to remove any residual detergent. It can be successfully applied by brush to avoid snagging "toothy" surfaces.

A 5% solution of Triton X-100 or Igepal is made in distilled water. One part of this solution is diluted with 9 parts naphtha. The mixture is whipped until a stable emulsion has formed. (If an even milder emulsion is desired, the emulsion may be diluted again with an equal part of naphtha, and whipped again.)

B-72 New Formula:

(12% B-72 in a xylene base)

Good as brush or spray. Good control of mat verses glossy when sprayed. Healthier formulation than toluene/cellosolve based.

250 ml B-72 (50% stock)
100 ml Diacetone Alcohol
100 ml Naphtha
550 ml Xylene

The following have been submitted by Carmen Bria, Western Center for the Conservation of Fine Arts.

Standard Varnishes:

8% B-72 in xylene 8%
B-67 in benzine 4%
B-72 in DEB

(Note: B-72 will not dissolve in diethylbenzene. First make stock solution in toluene, then add DEB).

Neutral Organic Soap Solution:

200 ml toluene
15 ml distilled water
25 ml oleic acid
10 ml triethanolamine

Xylene can be substituted for toluene.

Cleaner:

% triethanolamine in distilled water (have never used stronger than 10%)

The following have been submitted by Tatyana Thompson, Thompson Conservation Associates, Inc.

Standard Varnishes:

B-67 (see LACMA)
B-72 (new formula)
Soluvar

Ketone Resin N:

Stock 33% w/w resin in Stoddard

From Dienst Verspreide Rijkscollecties - The Hague (now incorporated in the Mauritshuis).

100 grams Laropal K-80 250 ml Stoddard Solvent

For brushing, thin to about 12% in stoddard (1:2). For spraying, thin to about 6-8% in stoddard or naphtha (1:3 - 1:4)

For matte, warm 6 to 8% solution in naphtha and dissolve microcrystalline wax (about 20 g in 500 ml varnish). Apply by spray.

Dammar:

Stock solution.
From Rijksmuseum.

100 grams Dammar crystals
300 ml Turpentine
When dissolved, filter

Recommendations: Hand select dammar crystals, use only palest. Use best available grade of turpentine. Make in small amounts, replenish often. Store in amber bottles. To use: Thin until pleasantly brushable with turpentine. To hasten drying, add a few drops of ethyl alcohol. May add a drop of acetone to clear solution. To remove streaks in old dammar varnish, add 10% ethyl glycol to brush dammar. Revarnish, streaks may disappear. (I haven't tried this --Tanya) Two ways to remove scratches in natural resin varnish: Reform the varnish with ethanol. Rub with beeswax, rub-out with soft cloth.

To make stock solutions from solid resins:

Acryloid B-67:

(45 solids w/w in naphtha)

200 grams B-67
325 ml VM&P Naphtha

Acryloid B-72:

(50% solids w/w in toluene)

200 grams B-72
230 ml toluene

The commercially prepared B-72 stock solution has cellosolve added.

If you are interested in seeing more favorite recipes, more can be published in subsequent Newsletters. This list need not be limited to painting conservators' formulae. Please send your every-day workhorse formulations to:

You may phone them to (on your dime) (213) 451-4135.

DISCLAIMER: These formulae are intended to provide an exchange of information from one conservator to another. Conservators who submit their formulae cannot be responsible for any undesirable outcome experienced by another practitioner. Further, it is not intended for any person who is not a trained conservator to use these formulae on works of art.