[Speedslug]

And I will add that the fuel takes an inch or three to burn once it leaves the torch face so you might be working too close to the torch.

You don't mention the kind of torch you are using but that picture looks a lot like my hothead torch work when I first started where I wound up capturing unburnt fuel in the glass.

Took me a long time to remember not to creep up on the torch.
My body just kept up with the habit of "closer is hotter" which is not true but it sure seems like it should be.