Thank you, everyone, for your comments. I am overwhelmed by the help given! I think I have written to everyone personally (and many of you have offered even more advice which is wonderful).
Here is one of Rayna’s:
and here is Karen’s.
I haven’t done any more playing with Paint Shop Pro this week but I know now to have a go with the posturizing effects and playing with contrast and brightness. I am going to print all the comments out and have another good go soon.
To summarize your comments, the black in the image is what will print. Grey will not work well so it is best to take as much out as possible. It is best not to have too much black all together or there will be too much of a ‘blob’ of colour when it is printed.
Mary suggested that I try and find a Print Gocco machine because the screens used for those (for fabric) are the same as those used in the thermofax process, so I have been keeping my eye out for one all week (that is probably why I haven’t been playing with the PSP!!). Strange how time disappears when you’re searching on Ebay and on the web….