National m-8 Question

[bob]

I have the National m-8 torch with the SM 21 tip. It's a great torch and I am thinking of getting different tips. I don't use my torch like you bead makers do but more for embellishments in my glass fusing. I am looking at different tips and it is kind of confusing. What is the difference between a surface mix tip (which I have) and a premix tip.
Bob

[shawnette]

Originally Posted by bob

I have the National m-8 torch with the SM 21 tip. It's a great torch and I am thinking of getting different tips. I don't use my torch like you bead makers do but more for embellishments in my glass fusing. I am looking at different tips and it is kind of confusing. What is the difference between a surface mix tip (which I have) and a premix tip.
Bob

Without getting all technical, Premix is for working with boro. Very harsh flame that's not good for soft glass colors. For soft glass, you want a surface mix.

[Mike H]

Hey Bob,

I use a National 8M and have all the tips but, I only use the surface mix tips for soft glass because as Shawnette wrote the premix tips will burn the color out of soft glass.
The sm-7 is about the size of a minor torch so you may be able to use that one too.

[bob]

Thank you both.
Bob

[cheng076]

Bob,

Premix means that the gas and oxy mix in a chamber inside the torch tip and then exit to be burned. Surface mix means that the gas and oxy mix after they exit the torch tip and then burn. Premix torches and tips give a hotter flame because the gasses are mixed more throughly before being burned.

PJ