A few years ago I reset knife blades in hollow handles using pitch bought in a semi-famous NYC silversmithing/jewerly supply house. I relied on the master of the house. The results were not positive. I find that the pitch (all pitches?) is hydrophilic and that the blade tang loosens up over time. In trying to repair the problem I heated the handle and found that the pitch, on getting hot, foamed up and putting that “genie back in the bottle” was frustrating. I restarted with new pitch, heating up to the point where I drove off all the moisture, refilled the handle inserting the tang and let cool off. That worked for a while but the same loosening occurred.
So, my question is how to avoid repeating the same mistake. What are better alternatives to pitch.
In my youth when I was an apprentice I had to make what was called cutlers cement, this was for the silversmith who regularly restored silver cutlery, to make this cutlers cement I used to melt pitch in a large saucepan and add plaster of Paris, which was stirred into the melted pitch, then I would pour the pitch mixture onto a grid of old 12 inch files arranged on a steel flatplate which provided the silversmith with 12 inch long sticks of cutlers cement when the mixture had cooled.
There is something I am not following.
My experience with the pitch is that is has some water in it. I do not know how much nor where it came from. But when I heat it up it will start foaming (from steam) if I heat it beyond 212*. The knives are washed in water, = more water. So I am wondering what happens to the Plaster of Paris which reacts and hardens with water. Problem?
Maybe the Plaster of Paris is used as a filler and my concern is overwrought? If only a filler is there anything else that could be used?
Apologies if overthinking, but I have already spent too much time resetting these blades. I want to to it for the last time. Thanks,
Stephen
Stephen, adding the plaster to the pitch makes the pitch a harder substance and less flexibility. The silversmith who showed me this process was trained at Garrard and had made up many sets of this type of cutlery. After I had made the sticks of cutlers cement for him, he would set the knife handles into a box of damp sand, then held the strip of cement in his left hand while heating it with a gas torch, melting the cutlers cement strip at it’s end so that it dripped into the hollow silver handle, when nearly full he would then heat the knife blade stem and then insert it into the filled handle. All I can suggest that it is worth a try for you, do some test mixtures of pitch and plaster and see what results you get.
The damage happens in the dishwasher. Everything goes in the dishwasher these days. Very few folks remember not to put the hollow handled knives in the dishwasher. Hollow handled knives should be hand washed. I think the flatware industry now uses epoxy.
“Cutlers’ Cement
(a) Rosin, 4 parts, to 1 part beeswax and 1 part of brick-dust, or plaster of Paris.
or
(b) 16 parts rosin, 16 hot whiting, and 1 wax.
or
(c) Pitch, 4 parts; rosin, 4; tallow, 2; and brick-dust, 2.
The opening for the blade is filled with one of these compositions.”
Be careful to check that the Plaster of Paris you use hasn’t had too many other ingredients added. Genuine Plaster of Paris is raw gypsum that is altered by heat to remove much of the water naturally occurring in gypsum. Also called “calcined gypsum” (roasted gypsum or gypsum plaster).
Whiting is powdered and washed white chalk (calcium carbonate) and is available from artists suppliers.
Hope this helps,
Cheers!
Lynette
We do not wash knives in the dishwasher. The only exposure to water is during hand wash. Using pitch alone, with the blades seated tight to the handle, the blades creep out and become slightly loose after a year or so. That is the reason for my inquiry.
I am a sliversmith by avocation, but I have been doing it for more than 30 years. My interest is more design and craft. The sterling silver set is a hand-me-down from my parents. This is my first encounter to “repair.” I am, however, a little baffled by the lack of a modern, more generally accepted solution to this problem.
And, I am mortified about how much time this has taken.
This is not to say I am not thankful for all the help.
Stephen
Coming at it from a different perspective. I’ve never made flatware, but I’ve scrapped it. Most knives use some form of pitch & plaster but I found some where the handles were filled with a low temp melting alloy of some sort.
The links in my previous post describe how the problem with washing is due to exposure to heat, not water.
Therefore, if your knife handles are not being soaked in hot water while washing, then maybe the problem is how and what you heated during the repair.
Notice James Miller’s description of using heat:
-heat the pitch, in order to mix in the plaster of Paris, then pour into the form of sticks, then cool.
-Heat one end of a stick of this cement with a torch while dripping it into the hollow handle.
-Heat the knife blade stem before inserting it into the handle.