This is the latest information received from the manufacturer:
"We have contacted the supplier of the paint. They think they have found the problem. The grains of the new paint are the same, (so they say) but they now think the problem is our medium. The paint is delivered as a powder, and we have to add medium to it to make it liquid. The medium we use is oil based, and they assume that the moisture makes the paint go “gritty”. So now they have sent us a complete prepared sample with their medium. We will receive that sample this week, so we can do another test next week. I will keep you informed how it goes."
Hopefully this means that despatches will recommence by the end of next week.
Thank you all for you continued patience with regard to this delay caused by the enforced move from a lead-based to a non-lead-based paint.