I was a bit fed up with my propane blowtorch because it loses pressure quite quickly and stop delivering the very hot flame necessary to heat the punches to the 'cherry red' point. I don't like canisters and disposable cartridges (I still write with an indestructible Parker 51
) so I decided to try the notoriously unsafe petrol blowtorches as recommended by Paul Koch in his Dolphin's article.
I purchased a mint 'BAT' blowtorch manufactured in the German Democratic Republic
and after reading all the safety recommendation published at: http://www.blotorches.com/horror.html
I gave it a try.
I filled the container to 3/4 of its volumen with benzine (wasbenzine), followed the starting protocol with alcohol (less smoke) and could make it deliver a very hot a powerful blue flame. Then I took a blank punch to the glowing red point in about 3, 4 minutes. Faster and more evenly than with the propane blowtorch. I liked it and I will continue using it.
So, provided you use a petrol blowtorch in good condition, have a lot of care handling a volatile fuel and operate it with proper knowledge of the tool; it's a very useful device for hardening punches.
Please if you decide to try one of these, please learn well how to operate it before doing anything: http://www.blotorches.com/startshu/startshu.html