[vmelkon]

I was wondering, if you want to make a slight vacuum inside your distillation setup (boiling flask and graham condenser and the rest), how would you seal the distillation apparatus?

Obviously ground glass on ground glass doesn't make a good seal.
I was thinking that silicone could be used since it sticks well to glass. The same type of silicone sold at hardware stores.
You would have to wait for it to dry.
Once you are finished, you would cut it to separate the boiling flask from the rest.

[Glassblower]

You should use,stopcock grease.Most lab suppliers have it.

[408]

Or teflon tape or sleeves.  Easier clean up and you avoid random signals in your NMR.  Plumbing section of the hardware store store for the tape.

When I distill under high vac, I do use grease as getting a good tape seal can be difficult.

[vmelkon]

I guess I would go for the teflon tape then since it is less messy. I've heard that indium metal sheet is used for hivac since it makes a good seal and there would be no vapors.