Little bit of info that could save you some dosh.
In the past I have thrown paintbrushes away that I have used for Hammerite,
it seemed that unless you paid for Hammerite thinners there was no alternative.
I did a bit of web searching and found out petrol will thin the paint and clean the brushes.
As a test, I have painted a 6ft boat rod with it and it looks great.It also covers the whippings very well.
It stands the flexing of the rod no probs.
I might have put hammerite sales up,but not for their thinners.Haha