How to remove old putty with a lead hacking knife?

29th February 2020


	How to remove old putty with a lead hacking knife?


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			Putty is used to seal glass panes into wooden frames. If the glass needs to be taken out, for replacement or repair, the old putty will need to be removed first.

			If the putty itself needs replacing due to wear over time, you will need to remove the old putty first. When putty gets old, it dries out and often cracks or erodes, reducing its weather resistance and its strength for holding in glass panels. Dry putty may become firmly stuck, making it difficult to remove.

			Most lead knives are tough enough to remove old putty, but it is the hacking lead knife which is specifically designed to do this. The wide spine at the back of the blade means it can be hit with a hammer, so that the cutting edge can hack into tough materials. Also, the hacking knife blade is not as sharp as other lead knives, which prevents damage being done to the window frame as the putty is chipped away.

			Step 1 – Position knife Initially, the blade of the knife should be lined up at a 90-degree angle from the line of the old putty, ensuring the blade isn’t touching the glass. If the blade touches the glass when it’s being struck, it will break.

			Step 2 – Strike back of blade Hold the blade steady and strike the back of it with a hammer. Use a moderate amount of force, so the putty will be chipped away a bit at a time. This should help prevent damaging the glass or the wooden frame.

			Step 3 – Move along length of putty Once some of the putty has been chipped away, the knife can be moved along the length of it. Hold the blade at about 45 degrees to the putty, near where the putty meets the frame. Strike the knife with a hammer as you move along and the putty should come off a bit at a time.

			Step 4 – Scrape last bits of putty away The point at the end of the blade of your lead knife can be used to scrape away any remaining bits of old putty.