Minimum putty depth

It's only about 5/64", can't see a problem, as you usually use glazing sprigs to hold in glass before puttying window.

 

You should be able to get 3mm easily but as said pin the glass first.

 

You can still get 2mm glass, but it's used mainly for picture frame glazing nowadays.

Float glass which is used for windows, picture frames, is readly available in 2mm,3mm & 4mm, plus other thicknesses.

Agree with Chippie, go with 3mm.

 

I wouldn't fancy fitting 2mm though if you were new to glazing.

 

Even fitting 3mm you have to be gentle with, it's very unforgiving & will crack if your heavy handed with bedding it.

 

That's never happened to me Guv

 

I once replaced 4mm with 6mm as it was a large window.
As has been said the sprigs locate it.
If you put a thick bead of putty in the frame and then push the glass in carefully so that all the back of the frame where the glass is covered in putty.
Then tap your sprigs in carefully with a pin hammer sliding on the face of the glass.
I think the glazing company allows an eighth of an inch all round so that when you compete the bevel on the front the glass is encased in a "U" section of putty and this together with the sprigs keep the glass in the frame.

 

How about just buying hardwood glazing beads insted of using putty, they come in various styles. You will then be able to paint and finish much more quickly.

 

Or rout and chisel out a couple of mill off the inner bead section of the rebate.

Mr. HandyAndy - Really