Hi All,
Thanks to the Painting Best Practices course, I finally decided to ditch flexible canvas supports in favour of mounting linen to wooden panels. Never knew the former could be so terribly problematic! However, with this change some new considerations sprung up which need clarification. So far the preparation looks like this:
For studies I plan to use some sort of solid wood support (or maybe HDF?; but certainly not plywood because it checks) impregnated on all sides with one or two applications of 10% solution of Paraloid B72 in ethyl acetate. Then I would put some Lead Ground/Acrylic Dispersion Ground.
For final pieces I will apply the Paraloid B72 as stated above and will then use pH neutral PVA adhesive to glue the linen to a birch plywood. The linen would be pre-primed with 2x GAC 200 and some Lead Ground.
The questions are:
1) Is the aluminum foil and low-density polyethylene combination a good alternative to Paraloid B72? Should the aforementioned procedure (ironing the aluminum foil onto the panel) commence on a bare wood surface or a prepared one (Paraloid B72)? Are there concerns over this practice?
For me, the thin aluminum sheet seems to be overly susceptible to tearing, abrasion and so on. However, it can’t be denied that it’s the best moisture barrier. I know for a fact that there are similar alternatives such as Marvelseal 360 and alkyd-based aluminum paints. These are expensive, though. What are your take on this as a whole?
2) Does the Paraloid B72 solution have a limited shelf-life like shellac? I don’t know if the one available to me has HALS/UVLS additives or not, but this is something to consider as the minimum amount sold is 1 litre. Also, can I apply Acrylic Dispersion Ground over this resinous sizing? Will the underlying varnish complicating matters as it remains redissolvable?
As a note to my last question, the potential problem I see with this practice is that solvents can penetrate into the underlayers and cause trouble when varnishing and cleaning. In any case, I decided to use solvent-based sizes over waterborne ones specifically to avoid fiber rising and warping.
3) When using solvents, can the Regalrez 1094 that has sunken in trigger the redissolution of the dried linseed oil paint or the leeching of unpolymerized free fatty acids?
This question is just me toying with an idea. I’ve learnt that some low molecular weight varnishes tend to sink in somewhat and that solvents, as they evaporate, can bring unbound substances to surface. My reasoning behind this notion is that the industry uses polymeric – high molecular weight – varnishes for acrylic paints because the surface is more porous than that of oil paints’. Ergo, the sinking in of varnishes is something that was found problematic, wasn’t it? I’m especially interested in your stance on this one. By the way, feel free to correct me if I’m wrong somewhere.
4) Can anti-fungal agents or anti-insect products be applied in any shape or form?
Sorry if I ask too much!
Thanks in advance,
Péter Hegedűs
Thank you for the quick answer and the reading, George! I sometimes feel guilty of overcomplicating things, but your response dispersed most of my concerns.
Peter
1. The use of aluminum foil as a moisture barrier was suggested in a technical note from the Canadian Conservation Institute: Low-Cost Plastic/Aluminum Barrier Foil – Canadian Conservation Institute (CCI) Notes
2. There is some evidence (Conservation – Wiki) that Paraloid in solution has a shelf:
The shelf life of B-72 is indefinite in dry bead form; it retains a discrete bead form and does not cold flow. Based upon the personal experience of conservators, a stock solution of B-72 appears to be good for a long time but scientists caution against keeping any stock solution for too long. A recent attempt to put B-72 resin beads purchased in 1972 into solution with Shell CycloSol® 100 resulted in a cloudy solution (Whitten 1997).
3. Low molecular weight varnish resins tend to sink in due to the small molecules more easily fit into the interstices in the paint film. Polymeric resins tend to hold out and not sink in.
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