Scale found on old 300 series Delrin

300Bucks

300Bucks

Joined
Apr 19, 2005
Messages
5,533
Some of you who 'gather' older 300 series Black Scale Delrin slipjoints may have encountered a grey scale or powder like material on knives that have been stored a long time. I have not yet found anyone to tell me exactly what that 'scale' is but I am guessing it is a deposit of the 'degassing' of the Delrin. If anyone knows please comment. Anyway I don't care for it on my knives so I did a test on a old beater 301. Knife was washed with a toothbrush and soap and water. Then it was soaked in mineral oil for 3 days, removed and wiped clean. The last two pictures were taken after 3 additional days of 'draining'. View photos for results. Proceed at your own desire. I am sure other oil and wax treatments may work as good, but everyone can get mineral oil...300$s:thumbup:


KNIFE AS FOUND

AFTER SOAP AND WATER WASH

AFTER 3DAY MINERAL OIL SOAK AND DRAIN

WHICH IS THE BEATER AND WHICH IS NEAR MINT
 
Last edited:
300$s good info. I have never got it on my knives but a lot of my electrical screw driver handles that do not get used for a long time and even some never used ones I have really get covered with the scale and I always wondered why and what it is. I have one quick wedge that has never been used but looks so bad you don’t want to touch it.
 
Nice report 300$. Top one is the beater, but can only tell by the rear bolster, not the scales!! :thumbup:
 
I have a 307 that the Delrin scales are faded or have some kind of whitening on them.

I did a search and came up with this old thread, so I'm gonna give 300Buck's solution a try.

Here is the before picture (I'll post after pics after it's soaked for a few days in mineral oil)

CF7A6DD2-3BFE-490B-9AFA-98333906283C-3278-000003E0CF86451F_zpsb63b7e11.jpg


I'm hoping mine turns out like the one in the first post...if it does I'll remove the scratches from the blades too. :)
 
Good info to bring back up. Lots of other knives beside Buck use Delrin. The mineral oil soak should help the joints also. Will be good to see your pictures, Stumps. Will have to see if I have any knives that are getting the whitening on them. I do have some Delrin "bone" knives that may need the treatment.
 
Good info. 300. I'm glad to see you start a new topic. I've seen that white on some of mine. DM
 
Many grades of plastic contain compounds generically called "plasticizers". This was especially true 30-40 years ago, when plastics technology was less developed. Nowadays the polymer guys have other ways of toughening plastic, but it used to be pretty common to toughen a plastic, especially a thermoplastic such as Delrin, but the addition of plasticizers.

Plasticizers do not react with the parent plastic. They are separate chemicals which settle between the strands of the parent polymer. These compounds act as internal lubricants for the polymer strands. The lubricated polymer strands move more easily past one another when put under stress. Which is to say, plasticizers act as toughening agents, allowing the strands of polymer to absorb energy, which would otherwise cause the plastic to crack.

Because the plasticizers are not bonded to the parent plastic, they are free to migrate through the polymer. Sometimes plasticizer will come to the surface of the plastic. It often migrates back into the polymer and life goes on. However, while at the surface, it can combine with small bits of dirt or other compounds. Once that happens, it cannot migrate back into the plastic. Over time, as more molecules build up, it can form a scummy sort of film.

While I don't know that this is the phenomenon which is responsible for the gray film on old 300 handles, it is a likely candidate.
 
Frank,

Your the man, till proven incorrect. Saving the reply into my 300 record. 300
 
I find it on the plastic buttplates of 1960's & 1970's era shotguns and rifles, especially Winchester's. I clean it off with a nylon toothbrush and gun oil, rarely ever comes back.
 
I soaked the 307 in mineral oil for three days after washing it in a detergent, then I buffed the bolsters a little and took a few scratches out of the blade. I tried my best to take the after picture the same as the before picture.

The before picture taken three days ago;

CF7A6DD2-3BFE-490B-9AFA-98333906283C-3278-000003E0CF86451F_zpsb63b7e11.jpg


The after picture taken a few minutes ago.

4-2-2013009_zps1242c0d0.jpg


There was very little work involved and I think it turned out pretty good.

I think 300Bucks was right with his method of bringing some life back to Delrin scales. :thumbup::thumbup:

Time to take it back out in the garage and put a nice edge on those blades to finish this project. Then I'll put it to use again.
 
Thats a really big difference there Stumps and with very little work " looks great " It just amazes me how well these old Buck knives clean up . I thought that I remembered reading something about using tooth past and a soft brush to remove that white scale from delrin .
 
Yep, Toothpaste or Mother's and a soft bristle is not a bad pre-mineral oil technique. 300
 
I still wasn't happy with this 307, so I did a little more work on it....after my nap today. :p

This first picture was taken a few days ago before the mineral oil soak.

CF7A6DD2-3BFE-490B-9AFA-98333906283C-3278-000003E0CF86451F_zpsb63b7e11.jpg


This second picture was the one I posted earlier today, but after seeing the picture, I wasn't happy with the bolsters.

4-2-2013009_zps1242c0d0.jpg


This third picture is after I sanded the bolsters.

4-2-2013022_zps6b1305ce.jpg


I also sharpened all three blades and now they feather paper nicely. It wouldn't even cut paper when I received the knife.

4-2-2013026_zps12201194.jpg


I think this one has a lot of life left in it.

I like what the mineral oil did and will keep this in mind next time I get Delrin that has whitened.

Thanks for the tutorial 300Bucks!! I'm all done now. :)
 
Forgetting one in your pocket and having it go through the washer and dryer works too.:o
 
skyhorse said:
Forgetting one in your pocket and having it go through the washer and dryer works too.:o
Click to expand...

Oh really, that's not hard to do. lol

Hey 300 how are the scales on the knife you started this thread with back in 'o8? Does it still look as good today without being touched since then? or do you regularly oil it?
Thanks
 
For what it's worth, a couple of years ago I aquired an old 301 (two spring) with a broken clip blade whose scales had also turned white. I ended up sending it Joe who managed to find one of the old blades for it. Prior to sending it in, I sprayed it with a product called "Tri-Flow" that contains P.T.F.E. (teflon), and the "white" stuff vanished. The only way that I can tell now that it's the one that I did it to is because I've kept it labeled.

The 301 hasn't been carried, used or exposed to the elements since then, so I don't know how that treatment holds up, but it seems to work well.
 
You must log in or register to reply here.
Back
Top