I'm a newbie with the stuff. At the moment, I'm playing around, but I'm learning a lot as I do.
A bit of research and I had the plan for what a section of the sort of drystone wall I want to build would look like. I got my bit of blue foam and went at it with my ballpoint in the suggested style.
I found a couple of things. Firstly, using Gorilla Glue to stick the stuff to other substrates was a find for me. Secondly, the stuff seems to drink paint. It's like MDF with a raging thirst.
First off, I gave my wall a coat of gesso, followed by Vallejo stone grey, a sepia wash and some drybrushing. And the whole lot sank in and almost vanished! So, I gave the panel two coats of sand coloured craft acrylic, followed by the sepia wash. Even then, I was surprised by how much wash it needed. I'm using Daler-Rowney acrylic ink, with just a touch of flow improver, and it still needed two coats to get a decent depth of colour. I think next time I might try priming with thinned PVA, as per MDF, before showing it any paint.
If you haven't come across them, these acrylic inks are a revelation. I've been using Winsor and Newton shellac based inks for nearly thirty years for art and modelling, but these acrylic inks from people like Daler-Rowney and Liquitex allow you to do things I had thought impossible. The pigment loading is enormous and hence also the staining power - which was why the need to use two wash coats was a surprise.
Finally, repeated drybrushings with shades of the base colour, grey, off-white and ochre as per normal to bring out a sense of depth and texture.
Well, here's the result. The panel is 40x35mm, so this is larger than life-size. This follows roughly the size of the drystone areas between the timber framings on the post-Roman rampart at South Cadbury.
First bit of blue foam!
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Notice the wall, compared to mine, is made of biggish stones (the rods are 1m), laid in courses on top of VERY big stones. Oh well, always next time. Ironically it will be quicker and easier to make the panels representing big stones!
Still, that's an authenticity problem, not a technical issue, and I'm sure the panel in question will "come in handy for something" as my late father would have said. I intend to be using this stuff quite a lot. As I live and learn I'll post a few things with ideas, experiences and hints that hopefully will be useful.