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  • Tackifier / plasticiser for carnauba wax based encaustic mediumApproveRejectUn-ApproveSubscribeUn-Unsubscribe
    Question asked 2018-07-25 19:53:57 ... Most recent comment 2018-10-11 21:34:43
    Paint Making Paint Mediums Encaustic
    Question

    ​I experimented with 100% carnauba wax and pigment on a hide glue gesso ground. As you probably know it was hard and glossy, but brittle, and it was easy to chip off. I am reluctant to add dammar because it may yellow. I considered Canada balsam, but after looking into it seemed that it might have the same problems as dammar. Could a hydrogenated rosin help, or microcrystalline wax? II found an article from the food industry that found polysorbate 60 was an effective plasticiser for carnauba, but I think that would make it susceptible to moisture. I  understand my responsibility to do my own tests, but any suggestions on what I might test? 

Answers and Comments
  • EditDeleteModerator Answer

    While I do incorporate a short exploration of historical encaustic techniques into my classes, I am not an expert in this medium. I will reach out to one of our moderators to chime in. However, I cannot resist making a few statements in the interim.

    My first question here is why start with an overly brittle material and add theoretical plasticizers to soften it? The other direction (eg softer wax with a harder addition) seems to have sufficed for a couple of millennia. In essence, why not start with beeswax and add a hardener to that to achieve your desired level of hardness/flexibility. Harder waxes like carnauba or candelilla or soft natural resins have been logical and compatible additions.

    Carnauba on its own is going to be very hard and brittle. It is usually added to other waxes to increase harness. While we do recommend against using dammar or any soft resin as an additive to oil paint, much of that is due to its continued its solubility in the solvents that would be used in any future conservation treatments, this is less of an issue with encaustic. The wax inherent in encaustic is always going to be sensitive to aliphatic and aromatic solvents, probably to a greater extent than the dammar. Therefore, the resin addition does not threaten the future existence of the artwork.

    Dammar does yellow to an extent, less so than almost any other of the natural resins. I have not seen comparative studies between dammar and Canada balsam but my own paintouts suggest that they are probably not hugely different in their yellowing in similar concentrations. A wax medium of 20% dammar and 80% beeswax should not yellow to a great degree. It will yellow a bit, however, and become slightly more brittle over time. Kept to this percentage, that should not be a problem as unlike oil paint, the wax itself does not yellow at all and this would not be a cumulative effect.

    If this were my preferred medium. I would experiment with stepwise additions of carnauba to beeswax to come up with a medium that fulfilled my needs. I would then compare this to a beeswax/dammar recipe to see if it differed greatly or offered any benefits.

    Brian Baade
    2018-07-25 22:28:03
  • ApproveRejectUn-ApproveUser Comment

    ​"The other direction (eg softer wax with a harder addition) seems to have sufficed for a couple of millennia. In essence, why not start with beeswax and add a hardener to that to achieve your desired level of hardness/flexibility"

    Good point. I didn't know what formulation had been used for millennia. And I guess because I'm compulsively curious and experimental,. But also when I experimented I liked the jewel-like quality of the pigmented carnauba. I wanted to see if I could get a tough film without yellowing for low pigment volume concentrations. If the yellowing of dammar at 20% is not very noticeable I might be trying to solve a problem that doesn't exist.

    If I want a tough clear film with no yellowing for low pigment concentrations acrylics might be a good idea.

    Also, a thin enough application of 100% carnauba and pigment absorbed into the gesso so that I could hardly mark it when I scratched it with my fingernail.

    2018-07-26 02:13:05
  • EditDeleteModerator Answer

    ​This is an older thread but I just received this very detailed reply from Richard Frumess, owner of R & F Encaustics:

    Here are some thoughts

    Rifka Angel. 

    I don't know if you're familiar with the painter, Rifka Angel. She painted in encaustic from as early as 1932 until her death in 1988. It is possible to consider her as perhaps the first encaustic painter in the US to consistently use the molten wax method (as opposed to saponified wax or wax in oil paint). However, she used, according to sources, carnauba and montan waxes rather than beeswax -- two extraordinarily hard, high melting point waxes. Having organized an exhibit of her work in our gallery in 2005, I found many of the paintings to be highly fragile. In some cases, large areas flaked off during transportation. Both the natural brittleness of the waxes and the difficulty in adequately fusing the paint without blurring the definitions of her composition would have contributed to its fragility.

    Carnauba as a hardener. You mentioned carnauba as a hardener for beeswax. We've done comparison tests between added damar resin (no solvent) and added carnauba. Damar resin, added incrementally increased the hardness of the beeswax incrementally; whereas carnauba added incrementally increased the hardness geometrically, going from hardening to cracking the beeswax with only a slight increase in the amount added. We therefore hesitate recommending its use as a hardener.

    Pigment as a hardener. However, a large contributor to the hardness of encaustic paint is the pigment. Some pigments make the paint film fairly soft, others make it quite hard. We did an 8-year test of several colors and were able to determine that, while they all go through a curing (hardening) process, that rate differs among the various colors.

    Yellowing effect of damar. The yellowing effect of damar on encaustic that you mention is noticeable mostly on the unpigmented medium. We've done tests in which we placed two sets of panels in different light settings to see the affect that light had on them. One set of panels was coated with white filter-bleached beeswax. The other was coated with encaustic medium (9 parts filter-bleached beeswax to 2 parts damar resin by weight) which is slightly yellow. The films were drawn down to a 10 mil thickness. One panel from each set was placed in a window sill receiving indirect sunlight. Two others were placed on a wall receiving ambient fluorescent light. The remaining two panels were put in a drawer. After several months they were compared to freshly coated panels.

    Window light. The beeswax panel in the window had bleached even further than its original whiteness. The encaustic medium, on the other hand, had darkened and yellowed. This was due to the heat affect of light that will darken damar, a fact noted by in papers by René de la Rie from the National Gallery.

    Ambient light. Both the beeswax and encaustic medium panels had changed very little.

    Absent light. Both panels in the drawer had darkened but not yellowed. This is a natural occurrence with beeswax and is easily reversible by exposure to light.

    Microcrystalline wax, in contrast, will darken in light due to oxidation, a condition that is not reversible.

    Best regards,

    Richard Frumess

    2018-09-26 10:52:22
  • ApproveRejectUn-ApproveUser Comment

    ​Richard, thanks very much for your reply. I found the information about the geometrical hardening when adding carnauba especially interesting. I have also noticed some pigments harden the wax, and a thin application at close to ideal pigment load wouldn't show yellowing. The addition of mica and wollastonite or any pigment that makes the melted paint thixotropic might also make it harder?

    2018-10-06 01:22:24
  • EditDeleteModerator Answer

    Thixotropy.  I am not familiar with wollstonite. But looking it up, I see that it is made up of about 50% silica. So what I know of silica in wax may be applicable. Silica will thicken encaustic. But whether it gives the paint a thixotropic property is hard to say since we’re dealing with heat, not brushing, transforming encaustic from solid to liquid. Even then, once melted, the shearing factor of brushing does not greatly increase the fluidity of the paint the way it does with a silica/linseed oil gel.

    Color affect. Testing of silica in colored encaustic has shown us that it has a slight dulling effect on pigment color. This is likely because its texture causes a diffusion of light.

    Hardening. Silica does not seem to have a hardening effect on encaustic. Encaustic with silica will harden over time, but that is more likely from the effect of the damar and the pigment on the wax than of the silica.

    Mica. As far as mica hardening the paint or making it thixotropic, my only reference would be our pearlescent colors, which are iron oxides & titanium dioxide bonded to mica. We do not find those colors to be particularly thixotropic.  

    Richard Frumess

    Owner of R & F Handmade Paints

    2018-10-10 17:15:28
  • EditDeleteModerator Answer

    ​Thanks so much Richard.

    It is really wonderful to have this info from all of your testing now on the site.

    Brian Baade
    2018-10-10 17:16:31
  • ApproveRejectUn-ApproveUser Comment

    ​Thank you Richard for your thorough replies. I said thixotropic but I should have said thickening. I was thinking of platy or needle-like filler/pigment particles. I am under the impression that they add strength to oil and latex paint films and that they might also lend strength to encaustic films. I thought that I might maintain a high pigment load and also make the paint transparent. But it seems, as you say about silica, that fillers are more transparent in oil than in beeswax. 

    I do think that encaustic brings out the beauty of transparent pigments like your Indian yellow. Encaustic brings out the beauty of colors that tend to yellow in oil, like Egyptian blue and azurite, Encaustic also brings out the beauty of some transparent Earth colors like catlinite and siderite. This is why I am asking these questions, and I do appreciate your generosity in sharing your time and knowledge. I understand better the reason for dammar in Encaustic.


    BTW 25% Canada balsam melted with 75% carnauba gave off overpowering fumes, was highly flammable, hard as a rock, and flaked easily off of a RSG/chalk ground, as people more experienced than me would have predicted :)

    2018-10-11 21:34:43
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