Something I found out by chance. Hammerite is popular with many, but the thinners cost about the same as the paint itself, at least where I bought mine.
I sprayed a white Transit I had until not long ago with Hammerite Smooth and........cellulose gun wash, ie cheap cellulose thinner. Five litres set me back six or seven quid. Not too shiny, but I suppose you'd get a better result with a better grade thinner, still much cheaper than the Hammerite thinner.
But for odd jobs, it's a really cheap way to thin Hammerite paint.
Yes, I think a lot gets wasted in over-application. I find it useful to use an initial very thin mix when any welding is ready for painting - like a pre-wash kind of thing, penetrating any little gaps and picking up dust, doubling up as the first primer coat.
And yes again, it sprayed very nicely indeed. Avoiding runs has more to do with skill in the mix than with the materials used. As I wrote, not high gloss, but looking in keeping with the age of the van.
On the subject of painting, I once thinned Sikkens Autoflex with household turps, brushed it on and got a really class finish. Once polished, it looked like a respray. Brushing can produce good results with a little work once the paint has hardened. Cheap too - you use much less paint. You have to keep flitting around the car though, picking up constantly on the wet edges before they dry. Add thinners as you go when the paint starts to 'drag'. I recommend a helper, so you don't have to stop and lose the wet edges.
If you get a fly landing on the wet paint during any painting job, just leave it there until the next day. It will easily rub out. Same with runs, just leave it all for 24 hours, then get the polishing paste on it. Heavy runs can be flatted with wet and dry before the polish. Quite amazing how something disastrous can look okay the next day!
Brushing, if you have the time, can be a good first coat before the spray gun comes in. The secret of brushing is a well-used, cared-for brush, the older the better. You can perhaps borrow one from an elderly 'handyman' neighbour - a much better source than the shops! Return it as clean as you found it, though!!!
For thinning hamerite I use 'Industrial Thinner' which can be purchased from any good automotive paint factors at about £15 for 5l. It is xylene based like hammerite which thins the paint without loss of finish. I clean my spray gun with cheap cellulose thinners.
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Huh - well I'm not lending my brushes to anyone ......
