Basic Grey Resin. Can it be used for casting?

So, I got a container of basic grey printer resin with my new Anycubic Mono X resin printer, and I have been learning the basics of resin printing. Lots to learn. Not like filament printing at all. Lots of failures, but getting there.

Almost at the point where I would like to make a metal casting, using the lost PLA/resin/wax method.

1 litre of basic grey resin costs about $AUD40.

On YouTube, the experts seem to be using special resins suitable for casting. For example Sirayatech Cast Resin. Costs about 3 times as much as the basic grey resin when postage from US, and taxes are added in. And about 6 times as much as filament on a weight basis.

But, I wondered, can basic grey resin be used for casting? It is MUCH cheaper.

So I performed a little experiment.

I placed two small PLA filament printed objects in the burn out oven, with a resin printed object of about the same size. And progressively turned up the temperatures.

On the left is a basic grey resin printed wheel bracket. Middle and right are filament printed PLA wheel and wheel bracket. All in the burnout oven. At 250ºc not much is happening. ( a quick door opening, photo, and door close.)
At 350ºc the resin object looks unchanged. The 2 PLA objects are melting.
Not a good photo, but at 430ºc the resin object is black, but retains its shape. The PLA objects have vapourised and disappeared.
This is the resin printed bracket after 15-20″ at 450ºc. It has left a shell of carbonised material. The PLA printed objects have disappeared. You can still see the bracket shape in the ash.
I let it cool down, and then crumbled it in my hand.

At the end of this simple test, I hesitate to title it an “experiment”, I have to conclude that basic grey printing resin is totally unsuitable for using as a “lost plastic” in metal casting. It leaves too much carbonised ash which would be incorporated into the melted bronze/aluminium.

OK. so I have ordered a litre of the expensive Sirayatech Cast resin.