Frit-Happens !

Jewellery => Jewellery tips, techniques and information => Topic started by: Moira HFG on December 04, 2013, 06:41:41 PM

Title: mouth blow torch advice please..
Post by: Moira HFG on December 04, 2013, 06:41:41 PM
I got a bit carried away looking at the discussion on small torches...I saw this one on ebay for a very reasonable £10 and bought it.
http://www.ebay.co.uk/itm/131055393675?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

Now I see it has an 'E' stamped on it, which according to Cookson's website means it is intended for use with natural gas rather than propane. I haven't got access to natural gas in my studio. Can I use it with anything in a canister?

Thanks.
Title: Re: mouth blow torch advice please..
Post by: mizgeorge on December 04, 2013, 07:13:34 PM
Not really - if it's got an E stamp it's for a plumbed in system.

Then you need to learn circular breathing ;) Not as easy as it sounds...
Title: Re: mouth blow torch advice please..
Post by: Moira HFG on December 04, 2013, 07:32:16 PM
Oh blast!

Actually I've got a head start with the circular breathing: my OH used to make didgeridoos, and we both learnt to do it! How's that for a happy coincidence?

So...what would happen if I put propane through it then? I understand natural gas is mostly methane, but do they really burn very differently? Or can I modify it in any way?
Title: Re: mouth blow torch advice please..
Post by: Magpie on December 04, 2013, 09:37:34 PM
I work in the science department at the local high school, we were in portacabins (very flash ones, don't think leaky walls and floors that move whenever someone walks) for a year and a bit while they rebuilt the school. We had to buy new bunsens for the portacabin labs that ran on propane rather than piped in gas. We now have a box of redundant bunsens as we're back on mains gas. I can't remember whether they just can't get hot enough or they'll take your eyebrows off, one or the other. If you don't get an answer I can ask my boss, she's a mine of info like that.
Title: Re: mouth blow torch advice please..
Post by: Moira HFG on December 04, 2013, 10:41:29 PM
Ah, that's interesting. At a guess, I would think propane burns hotter given that it has 3 carbon atoms where methane has only one....does that make sense, or have I just made that up?

I'd be grateful if you would ask your boss, thanks.

At the end of the day, it's just a steel tube with a control valve in it, and a second tube to huff some air into it. How different can the two types be? Certainly the propane and mains gas versions look the same on the Cookson's site.

I appreciate your help, both of you!
Title: Re: mouth blow torch advice please..
Post by: ARBeads on December 05, 2013, 07:47:27 AM
Didgeridoos, made me smile  ;D

My attempt at playing these was described as 'like and Elephant on heat', and involved the police turning up....... but that's another story  8)
Title: Re: mouth blow torch advice please..
Post by: Magpie on December 06, 2013, 11:11:15 PM
Boss says.........

She has no idea on how hot it burns. But you should be able to get a converter for it to run on propane, she says to go ask about it at a calor gas showroom/centre.

Hope that helps.
Title: Re: mouth blow torch advice please..
Post by: Helen G on December 06, 2013, 11:17:00 PM
Despite being sat down with the seemingly ancient goldsmith at college once a week to learn circular breathing, I can't do it to save my life :(
Title: Re: mouth blow torch advice please..
Post by: Magpie on December 06, 2013, 11:30:35 PM
Looked up temperatures: there seem to be as many different temperatures that methane and propane burn at as there are websites dedicated to them. But roughly they seem to be about 'the same', as in once you get to 2000C another 100C or so isn't going to make a difference. There does seem to be consensus that methane is slightly cleaner. However with regards to btu, it appears that propane is better, you need twice as much methane to generate the same amount of heat as the propane. So it may mean that the hole the methane comes through is larger so this adaptor that Alison was talking about would make the hole smaller (and hence why we can't use the propane bunsens at work because the gas hole is too small so not enough could get through to generate a decent flame).
Title: Re: mouth blow torch advice please..
Post by: mizgeorge on December 07, 2013, 01:35:12 AM
Quote from: Helen G on December 06, 2013, 11:17:00 PM
Despite being sat down with the seemingly ancient goldsmith at college once a week to learn circular breathing, I can't do it to save my life :(

I'm hopeless at it as well Helen - and I've been trying for years and years :)
Title: Re: mouth blow torch advice please..
Post by: Moira HFG on December 08, 2013, 10:43:59 AM
Excellent advice, Magpie, thank you. I will check out my friendly Calor gas seller for a flow restrictor.

I've been looking online for more information, and I find that these torches need to run at very low pressure - less than 1 psi or .05 bar (this is from Ottofrei.com, an American tool seller). So if I want to run it off the same regulator as my glass torch I'll have to keep changing the reg pressure - annoying - or set up a separate system. I do have a spare regulator. Would I need a flashback arrestor? I can hardly forget to 'turn off' the air....

Top tip for getting the hang of circular breathing: practice blowing through a straw into a glass of water, try to keep the stream of bubbles as even as you can.  ;)

Cheers, all

Moira