Using RSG to glue a finished painting to Masonite--acceptable practice or not? ApproveRejectUn-ApproveSubscribeUn-Unsubscribe
Question asked 2017-04-21 23:45:13 ...
Most recent comment 2017-05-02 07:24:45
Thank you for this wonderful website. So glad to see AMIEN has a successor.
I plan to paint on some RSG sized canvas and then (if the painting works out) to glue it to a rigid support. I had hoped to use my untempered Masonite as substrate to glue the textile to but recently read here that tempered is far better (however I don't hold out much hope of getting that product here in Australia). I am very much aware of all the disadvantages of using RSG (have been reading about them for decades) but I strongly prefer the working qualities it imparts to the surface I paint on. Also I understand that RSG is much less problematic when used on a rigid support, if all precautions are taken (such as sizing and priming both sides and also varnishing both sides at the proper time etc). I had planned to just go ahead and glue the linen to the Masonite and then do the painting (much more straightforward) rather than size a stretched canvas, paint on it and then glue it on to the Masonite. However I can't do this till I find a source of tempered Masonite. In the meantime I want to paint. My question is: is it unwise to use hot RSG to glue a finished painting to a substrate? Is it likely that the hot glue would damage the painting?
Answers and Comments
We are very happy that you find the site useful. It is true
that the conservation field would like to persuade artists from using RSG
because of all of the issues you are well aware of. I also understand the
reluctance of some artists to abandon this material due to the qualities it
imparts to stretched canvases.
So let’s ignore those issues for the moment and focus on the
suitability of using animal glue to adhere a finished painting to a rigid
support. First, as you suggest, it is far preferable to adhere the canvas to
the support before painting. You know this as well, so let’s move on. In the
situation you outline, I would strongly suggest that you use an acrylic
dispersion medium or gel in place of the RSG. It is less likely to cause issues
in the canvas while drying and creates a far better bond. Animal glues are very
strong and have great adhesiveness but are poor gap fillers. When gluing canvas
to a rigid surface, it is generally far better to use an adhesive that good
cohesion and fills the interstices of the reverse of the fabric rather than an
adhesive that has amazing adhesive strength but is a poor gap filler. We do
cover this subject to some degree in our RESOURCES section under Rigid
When possible, it is preferable to avoid introducing
moisture to a completed painting or one that contains an animal glue size. Water
added at this point may cause uneven buckling. This is not always possible and
is one of the reasons why it is best to completely prepare the canvas/panel
substrate before painting. You could possibly use a thermoplastic
heat-activated adhesive like BEVA 371 as well but that would depend on the
surface texture of your painting and the degree of impasto. I also suggest that
you allow the painting to dry for some time before even thinking about applying
heat to the surface. Again, you can read more about this in our Rigid Supports
To be perfectly clear from the begining, this procedure is not optimal, as you already mentioned.
I think that the answer to your questions is yes. Just to be
sure we are on the same page, I would not suggest sizing the hardboard panel
with animal skin glue and then use acrylic dispersion medium for adhering
canvas. This may cause problems as well and there would be possible incompatibility
(or at least solubility and dry time problems and issues). In place of this you
could size each size of the panel with the acrylic dispersion medium and then
adhere the rsg sized primed and painted canvas to this panel using the acrylic dispersion
medium. Done carefully, this should work fine, or certainly as well or better
than the using rsg to glue the canvas.
On the final though, varnish will likely slow down the
penetration of moisture into the stratigraphy but it would not really stop it.
If this were the case, the hygroscopic nature of animal glue would be not issue
at all when used on panel paintings. A final word of caution, though. Care
needs to be taken to restrict unrestrained movement of the canvas (weighing,
etc) to prevent any subsequent shrinking during the process (this is why we
always suggest adhering the canvas to panel before painting) to prevent damage
to the ground and painted surface.
We would not advise going this route however we are also not 100% positive that it wouldnt be fine in the long run either (as long as you document what you choose to use on the back). One concern would be that in places where the acrylic has seeped through the canvas weave, the RSG might not adhere well to these areas. Conversely, the canvas could also become less absorbent overall, therefore making your RSG layer function more like a coating (which is more problematic) rather than a size layer.
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