what is the deal with handles "curling" or shrinking ?

[hankist]

i have heard (and seen pics of) different kinds of plastic or synthetic handles shrinking or "curling" as some call it - i have a lot of older knives with delrin and other plastic handles in my collection , should i be worried about this? - i don't have any knives that seem to have this problem yet, but i have seen plenty of pictures of this on the internet - does anyone have any info on how long this takes to happen? , what causes it? , types of plastic this is more prone to happen to ? , does it happen to delrin? , bone? or what? , thanks in advance for any info - marc

 

[EDCanAdamas]

I can't comment on how long it would take modern plastics to "curl" or "shrink", but I doubt you need to be worried about it. The only knives I have ever seen with "shrunken" handles are old rubber handled camping knives from the 1930's and 1940's. Bone, as far as I know, turns yellow with age and does not shrink. Hope this helps.

 

[Alocksly]

The plasticizers in old plastics will evaporate and the shrinking/ curling is a symptom of that. More modern plastics/ polymers are better at this but you'll still see stuff that gets brittle and weak with age as it "drys out"

 

[liamstrain]

Celluloid is the most notorious for this. Others can, but not as drastically, that I'm aware of.

 

[hankist]

thanks for the replies , does anyone know about delrin ? - i have a bunch of camillus knives that i think are delrin but could be something else , remington bullet knives mostly , made by camillus , and some callimus branded knives , most of them have plastic handles , does anyone know if camillus used delrin or something else in the 70's into the 90's ?

 

[Bob W]

I have seen older plastics, celluloid, and some natural materials shrink or deteriorate over time.

But, as a semi-serious collector of Schrade Old Timer knives, I've never seen Delrin shrink. Never seen the red plastic on Victorinox knives shrink either. Nor the black phenolic handles on Buck knives.

Delrin does fade in sunlight though, and it gets chalky white if caught in a fire.

 

[knarfeng]

I have seen older plastics, celluloid, and some natural materials shrink or deteriorate over time.

But, as a semi-serious collector of Schrade Old Timer knives, I've never seen Delrin shrink. Never seen the red plastic on Victorinox knives shrink either. Nor the black phenolic handles on Buck knives.

Delrin does fade in sunlight though, and it gets chalky white if caught in a fire.

This.

I've carried Delrin handled knives for decades. The most degradation I have seen is the formation of a whitish film, which can be easily removed with mineral spirits or mineral oil. I've never seen any curling in Delrin.

Delrin was developed in 1960. Knives with synthetic handles made prior to that did not have Delrin handles. Some earlier synthetics, notably celluloid, are known to have issues with shrinkage.

My opinion is that any well made knife with plastic handles from the 60's forward should have little issues with degradation of the handle. As for the G10 and Micarta handles frequently found today? Those are made from epoxy or phenolic resins. Those plastics are stable.

 

[hankist]

ok - thanks - that sounds good - these knives are not all that old so i guess i should be fine - like i said , i don't have any that seem to have any problems yet - i just don't want to open a bunch of boxes up one day and find all my old new stock knives are shrinking away ! - marc