Following a few success stories in the studio using both Wolber’s new aqueous gels and the more established solvent gels, here is a step-by-step guide to the use of solvent gels to remove varnish from a 19th Century Qajar painting.
This painting had a thick yellowed varnish applied overall which fluoresced greeny/yellow in UV, suggesting a natural resin varnish. This layer was very difficult to remove using free solvents or solvent mixtures. We tested the surface with gelled cleaning solutions to see if through leaving a gel on the varnish surface for a few minutes or through adapting a water-based gel we were able to achieve better results. The most successful cleaning material was Benzyl Alcohol Gel, and here is how you make it…
Solvent gel recipe for polar solvents:
100ml Solvent (in this case Benzyl Alcohol)
20ml Ethomeen C25
2g Carbopol 934
10-15ml deionized water
Make the gel by mixing the Ethomeen, Carbopol and solvent. Add the water gradually using a pipette whilst stirring, the mixture with turn clear and begin to thicken. Stop when the gel is the correct thickness, if the gel goes cloudy you can re-balance it adding a bit more Carbopol/Ethomeen mix. It has a very long shelf life so you can make up a stock gel and leave it on the shelf, ready for testing.
It is very important to remember to clear the gel thoroughly, we did this by firstly removing the excess using tissue and cotton wool. The area was the cleared using a 1:2 IMS:White Spirit mixture first and then cleared again with White Spirit. This short time-lapse film shows how the gel was applied:
We left it on the surface for 5 minutes before removing it and, as you can see, the results are very impressive! Although gels have not replaced solvents in our studio they have certainly helped us to treat a wider variety of surfaces. We hope this helps if you want to try them out too.