Gerald, thanks so much for the information you have provided.
Now I need to order some sulfur and experiment. The potassium sulphide (poly) order from thrivechem.com is not going well they sent me an e-mail at 16:55 today, three days after the order was placed, telling me I needed to fill out the attached form and supply a scan if a piece of ID to make a purchase. Not a problem but there was no form attached to the e-mail and now they are shut for the weekend, typical British service. I will post results at a later date.