Question asked 2019-03-29 11:52:21 ...
Most recent comment 2019-03-31 19:41:30
I want to explore the idea of applying fixative or varnish to a metalpoint drawing. My reasons are:
1. I combine metalpoint with fairly developed egg tempera painting on panel (see attached as an example: metalpoint lettering & egg tempera rabbit on Golden black gesso); the work, to me, appears too "removed" from the viewer when framed under glass - so I'm looking for a way to frame without glass that will nevertheless give some protection to the surface; i.e. a light spray coating of B-72, followed by a wax medium.
2. In my metalpoint experiments (described in an earlier MITRA post) some metals and grounds, when exposed to a lot of sulfur, faded or completely vanished. I understand the lesson: trying too rapidly to speed up tarnishing can be detrimental to a drawing. However, it also points to the potential vulnerability of metalpoint lines; the insecurity of their attachment to a support. I realize there are many centuries-old metalpoint drawings in good shape, so I don't mean to say it's not a durable medium; only that it also has the potential to not hold up well. Additionally, I've heard two artists comment that drawings on "Plike" paper tend to "fade" or lose their metalmarks, but many metalpoint artists love working on Plike. Would a fixative be a good idea for those people who opt for the convenience of a pre-made, less-than-ideal metalpoint paper?
I understand that a fixative (depending on how sealing or heavily applied) may slow or completely stop the tarnishing effect, but what if an artist doesn't mind or actually wants to deter tarnishing? Would a light coating of fixative still allow for tarnishing?
In short, if fixatives are suitable for other forms of drawing, are they suitable for metalpoint as well?
Tho' I'm interested in subjective preferences, I primarily want to hear the objective, technical pros and cons.
Answers and Comments
You are probably have more experience with metalpoint than
anyone else on this forum so I would defer to you on moist issues associated
with the technique.
I do not see an attachment but will try to comment.
As far as fixatives, they are certainly a mixed blessing but
are sometimes necessary. Too much will darken the paper or gesso ground due to surrounding
the fibers/filler with a material of higher refractive index. Just the right amount
will help keep the particles from being too friable. Obviously only
non-yellowing fixatives should be used if possible.
I do worry that if there is enough fixative to slow or stop
oxidation/sulfation that the surface would really be quite saturated, changing
the overall effect. Of course, this is an aesthetic decision and the result may
be just what the artist is looking for (like your preference for lightly
varnishing your egg temperas).
I do not know what materials are used to finish Plike papers
but they are obviously more than simply 100% alpha cellulose or they would not
have the advertised feel of plastic and rubber and be resilient enough to take
a metalpoint line without damage. Perhaps the surface it too compact to hold
onto the abraded metal lines or one of the ingredients has a deleterious effect
on the metal? This would require more testing to make a determination on this
subject. I am very intrigued by your tests showing that the metal lines can
actually “disappear” when they are overexposed to sulfur. I cannot imagine what
the chemical process would be. Was this
liver of sulfur or another sulfur containing compound? If the problem is the
paper having too slick a surface, a fixative my help, if it is chemical, it
likely would not.
Sorry that is not a very definitive answer but it is all
that I can say given my limited knowledge here.
I had forgotten about Tom Mazullo and Susan Schwalb. I will
be purchasing that book immediately.
Plike papers may start out as 100% alpha cellulose but they
must be adding other materials, sizes, etc, to make a paper that can be
described as having the feel of a combination of plastic and rubber. Alpha
cellulose should only be a polymerized polysaccharide.
I am now wondering if it is not acidic conditions that are
causing a chemical conversion of the metallic lines. Vinegar causing lines to disappear
makes far more sense as metal acetates are often more transparent than alloys.
Onion and garlic both contain sulfur groups that when in contact with moisture
will convert to sulfuric acid. This is why your eyes hurt and tear when slicing
onions. Perhaps a similar thing is occurring with the liver of sulfur.
It would be very interesting to see if the same effect
occurs in a desiccated environment. I once put a silverpoint drawing in a
drying oven for a week or so and the lines definitely darkened some. When I get some spare time, I will do the same but include
some liver of sulfur. Perhaps this will accelerate the sulfation of the silver
but because of the very low moisture no acidic conditions would be created.
As to varnished metalpoint drawings on panel, the famous unfinished
Saint Barbara by Van Eyck is essentially a varnished metalpoint drawing on a
chalk glue ground with a bit of oil paint.
I've reached out to the Plike importer for more details on this paper and recommendations regarding fixatives. Will post if I get a reply.
Thanks Matthew. I was planning on doing the same but your assistance is of great help.
The Plike importer has reached out to the manufacturer for more information, but is not sure they will be willing to disclose any details of the coating formula. He said, quite directly, that Plike is not clay coated, and mentioned twice (with emphasis the second time) that Plike is made for commercial and packaging applications, and is (as we already know) not made expressly for metalpoint. (The trademark name "Plike" is apparently derived from "plastic-like".) He offered to recommend some other papers, and I said, for now, I would like to focus on Plike, for the benefit of artists using it, and conservation specialists who might have to treat works on this stock. I said that there would be interest in even the broad category of polymer used, and any recommendations for fixatives/top coatings. He did say to stay tuned, so there may be more to come.
This Page Last Modified On: