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Question asked 2018-03-29 19:56:43 ...
Most recent comment 2018-03-30 00:09:18
Dear Mitra staff
I have been experimenting with egg-oil emulsion mediums to add to oil paint (not as paint vehicles as such) and recently saw a reference to “gum tempera emulsion” (medium or vehicle) in Ralph Mayer’s Artist’s Handbook p.278. I was excited by this as I’d rather use a “vegan” emulsion medium if at all possible. The recipe is as follows: 5 parts gum (Arabic) solution; 1 part Stand oil; I part Damar varnish and 3/4 part glycerine. I’ve tried this on clay bird and it seems to be working OK. However I recently read a comment by one of your staff to the effect that gum Arabic is not a natural emulsifier. Does this mean this recipe is actually not really sound and that I should stick with egg oil emulsion mediums? I just want to reiterate that I’ll be using the mixture as a medium with commercial oil paints. I’m not trying to make my own paints. Kind regards, Jenny
Answers and Comments
I am glad that you posted.
What I mean by “not a natural emulsifier” is that, on its
own, gum Arabic has no real emulsification properties (ie nothing that forms an
intermediary between the aqueous and oily components). Before panicking, realize
that the same thing is true of animal glue and other materials that have been
used in emulsions; it is just that these are not stable emulsions in their raw
state. If left in the jars such an “emulsion” would separate into its aqueous and
oily components whereas one composed of egg and oil, or resin would stay
emulsified until it began to decay. A
couple of things to remember about gum Arabic is that it will eternally remain
water soluble/sensitive if used in any amount beyond the minutest proportion. Additionally,
it is extremely brittle as compared to more common oil painting additives. If you decide to use it in your works, please
record this on the back of your painting.
None of this speaks to their applicability as an additive to
tubed oil paint. What are you trying to achieve? Is there a particular effect
that you hope that said emulsion would help to realize? Please look as a recent
post about casein additives to oil paint. Partially mixed additives like these
can easily create heterogeneous, multilayer films that are prone to cracking
and delamination. Even if the paint is
completely mixed and an emulsion is achieved (very unlikely), the resulting
film is going to be much more brittle than a standard oil film with accepted
additives and mediums. It is also true that there are effects that can be
achieved using an emulsion such as this into an oil glaze or paint layer that are
difficult to replicate using more orthodox methods. One needs to experiment and
decide whether such effects are required to fulfill one’s vison or if the
desired quality could be achieved using more stable methods.
It seems to me that, for your requirements, and that you are
going to work on panel anyway, you would be better served by simply
underpainting in acrylic dispersion paints well diluted in water with no added
medium, and overpainting in oil. The panel would elevate any potential issues
of the flexibility of acrylic underlayers (probably way overblown anyway).
I can see no advantage, given your rather simple needs for
this layer, to introduce a complicated, potentially problematic paint layer to
what could be deleterious to the longevity of the work. If you were seeking a
difficult to achieve paint effect the answer may be different…but probably not.
In general, it is better to keep things as simple as possible and yet still
achieve the visual effects your artistic vision requires. It is ok to deviate from
best practices to create a necessary effect, it is foolish to do so to achieve
an easy to accomplish one.
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