clear yellow handle screwdrivers

[mechanic10]

I know there was a problem with the early black contour grip screwdriver handles breaking down chemically.I had a magnetic screwdriver from late 70's.It got so bad it was rusting other tools in same tool box.My snap-on dealer finally took it back and replaced it.
My question is were there any problems with the clear yellow handles ? Also does anyone know what years were affected of black contour grip handles ? Is there anyway to tell if they are subject to chemical breakdown.

[J.A.F.E.]

It was the original black handle design - I believe they were called Tennite after the material they were made from. I don't think all were subject to breakdowns as I bought a bunch of them new and all except one are still fine. The one that broke down was a gasket scraper with the screwdriver handle. The later style black handles do not seem to have the reputation for breaking down.

I have a few of the magnetic drivers with the black handle and have never had any issues with those.

I have some of the yellow handles and they are as far I know stable. Snap-on used them for Snap-on drivers and later Par-X and BluePoint drivers as well as nut drivers.

[snapmom]

So, what causes everything to start rusting when a handle gets cracked like that, I had one that did that too, and had rust on everything around it.

[J.A.F.E.]

As a wild guess some of the breakdown products must be acidic.

[mechanic10]

Would it be safe to assume that if the handle was going to go bad that it would have happened by now.The one that I had that went bad was from late 70's.Also i now remember having a straight blade handle go bad,but the snap-on dealer only replaced the handle on that one.
I still have 2 other screwdrivers from early 80's that seem to be ok

[J.A.F.E.]

Hard for me to say. I often wonder if the handles were affected by grease and gas. Mine were all kept clean and I have so far had only one disintegrate. That one was on a gasket scraper and saw a lot of solvents and grease and such. Perhaps a coincidence i don't know.

[davewho1]

I have a couple of yellow handled drivers and they're fine. I bought my set of black handled drivers in the mid-80s, and never a problem with them.

I did get a black 1/4" socket driver handle at a yard sale a while back and it is flaking and peeling. Can't recall if there's a date code on it, and now I can't find it.

[engineer61]

I had three of the black handles from the late 1970s or early 1980s, and all broke down. One was a pry bar, one a magnetic screwdriver, and one a 3/8" sq dr stubby handle. All of these had light use and were always kept clean, and I really don't think oil or grease played any part in it.

As far as I could determine, the stuff that oozes out is the plasticizer that keeps the plastic "plastic", ie non-brittle. I don't know what the goo actually is, but it has an acrid smell and seems to be acidic - I know this because I found out the hard way that it strips the paint off a Snap on tool chest!

Here in the UK Snap on really didn't seem interested in the problem and did nothing to replace the tools. At the time I noticed this problem I didn't have access to a local Snap on man, so I wrote to the UK head office. In fact I wrote three times, each time enclosing a return envelope, asking for advice, if it was covered by the warranty, and if the arrangements could be made for the tools to be replaced (and would they like to replace the damaged chest as well). Sad to say that I didn't receive a single reply! So much for customer service! After doing some research on acidic plasticizers I suspect that the goo is also very bad for your health!

In the end I binned the mag screwdriver, put a wooden handle on the prybar, but I still have the stubby handle, now stored away from everything else, with its handle slowly disintegrating.

I have some Par-X yellow handles from the same era and they are still in as-new condition. Also the later black plastic handles also seem OK.

I think it was just a short period when the plastic used was unstable.

PS - I think that material is actually spelled "Tenite". Google can provide more information.

[engineer61]

Done some more research on this....

The handles are made from some form of Tenite, which breaks down eventually exuding Butyric Acid (also known as Butanoic Acid). The acid is the goo which forms on the surface of the handles, and is also what makes the "rancid butter" smell. Being an acid, it attacks paint, metal, and just about everything else it comes into contact with. The acid also accelerates the breakdown of the tenite, which in turn produces more acid, etc etc.

As the acid is exuded the plastic shrinks, which causes the handle to deform and crack.

The rate at which Tenite breaks down is apparently temperature related - the warmer the storage the quicker the breakdown. It is also irreversible and unstoppable (might be worth keeping those historic collectible tools in the freezer)!

Butyric Acid is classified as a hazardous substance by the EPA.

Some later tool handles seem to form a white chalky gunk on the surface, which at present I haven't been able to identify. It is likely that this is a later form of Tenite which is breaking down in a similar, but slower way.

[ToolMike]

The decomposing handles were made from Eastman (Kodak) Tenite material (Cellulose Acetate), molded by National Lock Corp. (Rockford, IL.) for Snap-on in the early '70's. There were a few batches made, we were told, made using a non-Eastman plasticizer as a cost savings for National Lock. As you might gather, Eastman's Tenite was very expensive, as was their plasticizer and people were cutting cost corners. The upside was that when made to spec., the Snap-on handles were impervious to just about any grease or solvent, except Skydrol (aircraft hydraulic fluid) and concentrated Acetone.
I had a few screwdrivers from a bad batch that pretty much stripped the paint from the inside of my rollcab drawers...and did they stink! The amber handles were not molded, but were lathe turned from extruded Tenite stock supplied by Eastman...i.e. no middle man to muddle the chemistry. At any rate, those Snap-on Tenite handles made up into the late 1980's were the most chemically resistant handles you could manufacture.