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MITRA Forum Question Details

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  • Gum-oil emulsion medium ApproveRejectUn-ApproveSubscribeUn-Unsubscribe
    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

  • EditDeleteModerator Answer

    Hi Jenny

    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.

    Brian Baade
    2018-03-29 22:43:53
  • ApproveRejectUn-ApproveUser Comment

    ​Thanks for your clear and helpful answer, Brian. What I was trying to achieve, I guess (apart from experimenting  for its own sake) was to find a way to produce a fairly simple underpainting that would be “self sequestering” to use Tad Spurgeon’s term, under my oil painting. It seems this emulsion probably wouldn’t fit the bill, though, if it’s fairly fragile as you say. And I certainly don’t want to introduce problematic brittleness into my painting, even though it will be on board.  What I really want is an underdrawing in paint or an underpainting that won’t budge,  so that if, as the painting proceeds, the gremlins start to take over and drag it to the “dark side” (speaking metaphorically!) I can wipe away later layers of paint and get back to a firm underdrawing/underpainting so that I can start back from that. 

    2018-03-29 23:27:20
  • EditDeleteModerator Answer

    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.

    Brian Baade
    2018-03-30 00:09:18
  • ApproveRejectUn-ApproveUser Comment

    ​Thanks Brain; I’ll give that a try. Simplicity is best sounds like a good approach. 

    2018-03-30 00:20:45

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