[confused concept] do we really need sizing? ApproveRejectUn-ApproveSubscribeUn-Unsubscribe
Question asked 2023-04-26 13:02:29 ...
Most recent comment 2023-04-28 00:29:07
Grounds / Priming
Oil Paint
Rigid Supports
Art Conservation Topics
Hi here,
i am using acrylic gesso to prepare surface on raw fabriac canvas and tempered hardboard for oil painting.
so from people saying first step is to use a kind of gloss acrylic medium to "size" the substrate first, before applying acrylic gesso.
my question is, what is the real difference between acrylic gloss "size" medium and acrylic gesso in terms of material? can we apply acrylic gesso directly on susbtrate as size, primer and gesso purpose all in one?
from what i reads, the gloss medium forms a more sealed surface that seals the substrate, so water or oil content from subsequence layer will not sink into the substrate anymore, but if it is a very sealed surface, how can acrylic gesso adheres well on top, we all know acrylic bond on porous surface only.
in addition, i recently notice GOLDEN company revised saying no use of gloss medium under oil painting otherwise it would crack. so if we apply acrylic gesso, which is porous materila in nature, directly to substrate, what would happen? will that not adhere well to substrate? will that very porous so the oil will sink into substrate?
OR, it is absolutly a best practice to apply gesso directly on substrate? if so, since acrylic gesso out of bottole is thick, do we want to dilute it very thin for fist layers, then slight dilute in latter layers?
as i see Lascaux instruction, always dilute very big amount like 1:2 while other manufacture said cannot dilute more than 20%? so i am very confused.
EditDelete
Moderator Answer
(gwatson@goldenpaints.com)
We no longer recommend using a glossy acrylic medium to size before using an Acrylic dispersion ground (Acrylic Gesso). Three coats of Acrylic Gesso is sufficient to block oil penetration into canvas and does not require a sizing product. More layers can be used if desired. Different brands have unique formulations that can handle differnt dilutions with water. This may have to do with the amount of solids vs binder. Just go with their recommendation and you should be fine. They have likely tested for their products best performance. GOLDEN Gesso is already thinner than most, so we recommend about 20% max dilution. Acrylic Gesso is a stable base for oil painting.
Glossy mediums are simply binder with minimal ingredients to modify viscosity/rheology and feel as well as to provide some shelf stability. Acrylic Gesso has a similar acrylic base material, but with the addition of inert solids and white pigment to provide covering and tooth/absorbency. Thinness and thickness in acrylic is determined by the amount of thickener added, and has less to do with the quality or the amount of pigment or other ingredients in the product. All waterborne acrylics dry to a porous surface and adhere well to themselves regardless of sheen.
EditDelete
Moderator Answer
(mkinsey)
We have recommended Acrylic Sizing (low-viscosity, high strength polymer dispersion) as an optional step for canvas, to reduce strike-through and to enhance adhesion with acrylic dispersion painting ground (Gesso). Acrylic sizing promotes a strong bond with the primer and pre-shrinks and stiffens the fabric, however virtually every professional-grade acrylic gesso we're aware of can achieve good results when applied directly to untreated fabric, according to manufacturer directions.
EditDelete
Moderator Answer
(mkinsey)
The product Utrecht Acrylic Sizing is a low-viscosity (very thin) acrylic dispersion product formulated specifically for use as a sizing on fabric and canvas. Other acrylic mediums can also be used for this purpose. When applying an oil priming, it is always recommended to apply a sizing. When priming with acrylic dispersion painting ground (gesso), however, it's not stictly necessary to use a separate sizing because gesso adequately isolates the fabric from the paint. As an optional step, applying an acrylic-based sizing before gesso can stiffen and tighten the fabric, and reduce porosity so there may be less gesso travelling through the canvas weave to the back. Adhesion between acrylic layers is strong, so an acrylic-sized canvas has an overall very receptive surface for gesso with uniform appearance from corner to corner. This is by no means a necessary step, but some artists find the results quite desirable.
This Page Last Modified On:
restricted
