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Alternatives to GACs

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​Hey,

Lately, Golden advises against using glossy acrylics in any preparatory layers for oils. In light of this, what would you substitute GAC 200 with? I’m using linen, stretch it first, size it, then add 2 layers of oil ground and last but not least I glue the dried canvas onto an aluminum panel with a PVA glue. I would like to have good oil blocking properties. I’ve been thinking about getting RSG, but I don’t know how it can affect even a glued down canvas. It for sure will have less deleterious effect on the painting given the rigid support, but it can still soften (I think) and maybe move a little bit with very high humidity. PVA is another option but I’ve heard that it’s not good at oil blocking. With regards to acrylic grounds, I’m a bit wary of using them in light of the recent findings regarding other types of acrylics. 

What would you size your canvas with before applying the oil ground?

Thanks,

Peter

​As a fellow artist what I’d do with this problem, is have a single thin layer of acrylic gesso between the GAC and the oil ground.  The GAC sizes the linen, the gesso will stick to this, to which the following one or two layers of oil ground will adhere.
It may not be pure oil ground, but it would function as one.  You’ve already accepted the use of acrylic resin anyway.  The further use of another acrylic product solves any issue this presents.
Marc.​

Thank you guys for your answers! I guess I’ll go with the PVA option.
​To clarify, so far I used GAC 200 for sizing, and PVA for gluing the canvas to the panel. So, now basically I’m going to swap the GAC 200 for the same PVA adhesive I use for gluing.

​Regards,

Peter

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Hello Peter,
It sounds like you are already sizing with PVA before your oil ground application.? If this is the case, then perhaps you should stick with that, especially if you are using the same material to adhere the canvas to the panel. The fewer types of material in the structure of the painting, the better. That way you do not have many different materials aging differently and being influenced by environmental factors differently as well. In general, if there is not a specific reason to use the RSG (ie tightening or stiffening fabric) then we recommend keeping it out of the system.​

The primary benefit of the GAC 200 is that is can block oil AND stiffen the fabric. The stiffening is less important if you are adhering the canvas to a panel. An alternative to PVA would be to size/prime the canvas with 3 coats of white acrylic gesso/dispersion ground before the oil ground. This will block oil and we have not seen any cracking issues with oils over gesso. Oil ground can be applied directly onto the gessoed surface after 3 days dry time.  Then you can use an acrylic gel to adhere to the panel. Here is a link to a video showing the use of Soft Gel to adhere paper to panel. You could use the same technique to adhere canvas to panel:  https://www.goldenpaints.com/videos/applying-paper-to-boardadhering-watercolor-paper-to-panel-using-golden-soft-gel
We have seen slightly variable results with PVA in terms of oil penetration. We test with 3 drops of refined linseed oil directly onto the prepared canvas. With PVA we see it takes 3-4 coats to block straight oil. This is a very rigorous test, as most grounds or colors dry much faster and are less likely to strike through after 2-3 coats. This is particularly true if you are using an alkyd based ground which should dry overnight. For most applications, 3 coats of PVA should be fine.

Best regards,

Greg Watson 
Materials & Application Specialist
GOLDEN Artist Colors​

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