Hi Sue,
1. How should I seal these (charcoal and pencil) before applying an isolation coat?
Ordinary fixative will be fine, it won’t discolour the paint.

2. Would you go on to varnish a piece like this?
Personally I would varnish a piece after applying an isolation coat. I’ve haven’t touched on Varnishing in the tutorials as the isolation coat gives you the flexibility to come back to your painting and tweak parts. Once varnished, this is harder to do. I am working on an article about varnishing at the moment for the blog, so will add this information to Lesson 12.

3.What is common practice amongst contemporary artists?
Most artist do varnish once completely happy with a piece.

4. What are the different merits of matt vs gloss varnishes or glazing mediums?
The glazing mediums are used before you would add an isolation coat.
I always use gloss medium because there is less colour shift, and the isolation coat evens out the gloss finish afterwards.
The merits of gloss varnish is that it helps to bring out the colours of a painting. Sometimes, however, aesthetically a matt finish is preferred.
The matt varnishes are fine but because they contain a matting agent which is white (but dries clear) they can sometimes add a milky finish to the blacks. You can reach a happy medium with a satin varnish, but just have to make sure the pot is mixed well because the matting agent can sink to the bottom of the pot.

Hope this helps,

Will

Hi Sue,

Yes to confirm, you can spray fixative onto the dry acrylic without damaging the paint or affecting the adherence of the isolation coat.
You’d always have an isolation coat under varnish anyway, so the Varnish sits on top of the isolation coat that sits on top of the fixative.

Do you have any suggestions as to what medium is best to use when drawing onto dry acrylic?

As Acrylic is plastic based you will have trouble drawing on top of thick acrylic paint with pencil or charcoal. It won’t make a mark as it won’t have anything to adhere to.
There is a medium called Golden acrylic ground for pastels that you can apply to your painting, it dries translucent but gives a ‘tooth’ for drawing on top of. Below is the information taken from the Golden website.

Is it possible to use an oil stick onto acrylic?
Yes, it is possible, but an isolation coat cannot be applied to this as the oil needs to breathe.

Hope this helps

Will

PRODUCT DESCRIPTION

GOLDEN Acrylic Ground for Pastels is a 100% acrylic medium designed to prepare surfaces for the application of pastels, charcoal and other art media where a coarse tooth is desired. It contains finely ground sand (silica) in a pure acrylic emulsion.

Acrylic Ground for Pastels can be applied to paper, canvas, wood or any primed support. This allows almost limitless applications for media typically confined to standard papers.

PRODUCT APPLICATION

Thinning
Due to the weight of the solids in Acrylic Ground for Pastels, it is produced very thick, and does not come ready to brush-apply. Thin 20-40% with water to desired consistency.

Application
Apply with brush, paint-roller, spray equipment, squeegee or palette knife.
Mix up only as much as is needed for one day’s work, as the solids will settle rapidly and be extremely difficult to mix back into suspension.

Surface Preparation

Non-absorbent surfaces should be abraded for increased adhesion. Prime with GOLDEN Gesso or other suitable primer (depending on substrate).
Apply one or more coats of GOLDEN Acrylic Ground for Pastels to achieve desired tooth.
On paper, use heavier weight stock to avoid buckling.
Allow ground to fully dry before applying media.

ADDITIONAL INFORMATION

Use as a Ground
For best surface adhesion, apply GOLDEN Acrylic Ground for Pastels over GOLDEN Gesso. It may also be applied over other GOLDEN acrylic mediums, gels, and paints for multi-media work.

Note: When used in conjunction with oil-based media, prepare support (canvas, linen, masonite, etc.) with GAC 100 to block the oil from penetrating into the support, which can weaken or rot natural fibers. See GAC Specialty Acrylic Polymer Medium Information Sheet.

Use as a Transparent Gesso
Like GOLDEN Matte Medium, Acrylic Ground for Pastels can be used as a transparent gesso. Both can be applied directly to substrates. The “toothy” quality helps media to adhere, yet allows the underlying layers to remain visible.

Note: both products dry with a whitish translucency, and multiple applications respectively increase visibility. Test all applications prior to use.

Hi Sandi,
I water it down so it has a better consistency when brushing on, due to the thinner application it also has a more translucent finish. The isolation coat straight from the pot won’t do any damage to your picture, it just will be harder to apply.
Will