Chris Bacon wrote in :

On 10/09/2020 22:07, Stephen Duppe wrote:
I think the 123 contains chalk. Could be that they wouldn't be
in breach of the Trades Descriptions Act if they marketed it as "gesso"?

FWIW I was at Aldi this afternoon, they have "chalk paint" in litres at
a fiver. No idea what it's like, can't remember who makes it, you could
have a look (or not!). Colour: "Clotted Cream".

Ah yes, "chalk paint". I've heard of people using this ultra-matt stuff on furniture and then "distressing"
or waxing it. I haven't heard of it used as a ground on art paintings before, or as an undercoat of any
description, but since some may contain chalk I will investigate. Thanks for this.

I am in the process of "reclaiming" four canvases, using both Winsor and Newton "professional"
gesso and Zinsser 123 and can report as follows.

The 123 has been better at blanking out the underlying colours that have been worst at showing
through - worse than black - namely blue and purple.

The gesso dries matt; the 123, satin.

Neither has been great at hiding brush strokes. I will investigate using washes with both and also
sanding.

123 as a satin ground with gloss colours applied on top might be right up my street, with no need to
varnish the canvas later.

Stephen