I don't know if the answer to that question has ever been asked or covered. Nor (in my opinion) has the time span for the use of Delrin been documented or accurately defined. Mr. Gaddes did not address Delrin in his book and what has been written here and there on occasion have been declarative statements issued without backup data, that were then repeated as fact until it became circular scholarship (where have I seen this tendency before?).

But I can speculate about Randall-Delrin based on on-going occasional research into the product, and examination of the published Randall knives with Delrin handles (there aren't many).

Delrin was developed commercially about 1960-62 with the opening of a plant to produce it, but only after some patent issues (I think). Randall apparently first used Delrin shortly thereafter, probably by about 1964 at latest, based on a picture of a "SS" knife with a Delrin handle. This was at a time when the shop was apparently experimenting with different handle materials, including micarta, as a possible alternative to Tenite ... which had a cheap plastic look to it.



Delrin continued to be used off and on by Randall, under the moniker of "ivorite" until the end of the 1960s-early 70s, or so. But it apparently not many knives were made with it. Why? I speculate that the success of Micarta as an artificial handle material made the use of Delrin moot ... except for those that wanted a specific ivory look without the cost of ivory. At this time ivory was readily available but cost bucks.

With the further development of Micarta as a material in the early '70s with new colors including gold and white, Delrin was probably superseded by market demand and shop preference and decision. It would make production sense to limit the number of artificial products used for handles.

But what is interesting is that Delrin was also developed by others as a handle material for knives in the 1960s and 70s. Many colors were indtroduced including multi-colors that resemble stag, and the material went on to become possibly the most common knife handle material ever used ... because most of the Swiss army knives use Delrin for their scales even today.

There are some misconceptions (my opinion) about Delrin.

1. It discolors... well not so much... it is easily cleaned.

2. It is too soft and is easily marred. Well, nope. It is quite hard, harder than Micarta and Tenite and is difficult to scratch. Indeed it is used for ball bearings, billiard balls, and the stock of the M-16 rifle. Don't know where the "soft" rumor started.

3. It is too slick feeling... well, yes it does have a a slick feel, but so does a well-used ebony handle. The difference is that the Delrin feels cold and ebony feels warm. I suspect the cold-slick feel put off some people, like holding a cucumber just taken out of the refrig.

4. The initial limited colors and artificial look of Delrin WHEN MR. RANDALL EXPERIMENT WITH THE MATERIAL gave it an artificial translucent look. Yes, this is true in my opinion. The early colors were only black and white and brown (there is no indication I've found that Randall used any Delrin color other than white) ... and were not particularly attractive especially compared with solid substantial look of Micarta. But that changed by early '70s with development of the coloring process for the material.

Summary... I suspect that the development of Micarta as a handle material in the mid-lkate 1960s superseded Delrin and limited its use to only substitute ivory. Better coloring of Micarta then caused Randall to quit offering Delrin entirely though it may have appeared occasionally into the 1970s. Without the development of Micarta, Randall might be using Delrin today.

Footnote: I still have a suspicion that General Westmoreland's famous ivory handled APFK actually had a Delrin handle.
Footnote: This line is suppposed to be dedicated to matched pairs and I have diverted it to Delrin. Perhaps a general topic opened in the other forum would be more appropriate. Regards.