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What Kind of Plastic is This?

10/22/2021 8:06 AM

Craftsman screwdrivers oxidize (I assume) with a white film that can be scraped off with your fingernail leaving a smooth surface. I have noticed this many times over the years. I have never seen this with any item other than Craftsman screwdrivers. What kind of plastic is this?

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#1

Re: What kind of plastic is this?

10/22/2021 8:08 AM

I think this happens to most plastics stored in a damp dark place....

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#2
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Re: What kind of plastic is this?

10/22/2021 12:36 PM

..."Clear plastic screwdriver handles are usually made from cellulose acetate butyrate, a material developed in the 1930s. Its primary component (cellulose acetate) is made by reacting the cellulose from wood pulp with a variety of acids."...Oct 8, 2017

https://www.popularmechanics.com/home/tools/how-to/a28534/plastic-screwdriver-handles-smell/

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#5
In reply to #1

Re: What kind of plastic is this?

10/22/2021 9:21 PM

Part of me would love to disagree with damp and dark but they do seem to be right on target. The old, lost tool box that was under the work bench and on the concrete floor for about a decade seems to be the championship environment for growing the white stuff on Craftsman screwdriver handles. Other places are not immune and these were not controlled experiments but dark and damp did seem to have the most growth.

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#18
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Re: What kind of plastic is this?

10/26/2021 1:17 AM

Most plastics are highly water-resistant. That's one reason they are often used to replace wood in tool handles and elsewhere. Some have additives for color or to resist sunlight, or to make them even tougher in impact. The whitening sounds like exuding of an additive and shouldn't happen. There is the added problem of the sale of the Craftsman brand in 2017 from Sears to Stanley Black & Decker and thesubsequent offering by Sears of similar products, and then the pandemic, so I couldn't say who makes/made what where any more.

Screwdriver handles used to be made of cellulose acetate-butyrate (so were car steering wheels) but that was years ago and the cost of CAB is maybe too high now. It is seen correctly as an "old" plastic. Maybe someone has the CAB molds for handles somewhere overseas and still uses this material. It can be identified by burning odor and density. Major US supplier is Eastman Chemical, from whom you can probably get more details.

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#3

Re: What Kind of Plastic is This?

10/22/2021 12:56 PM

A polymer that lacks additives for UV protection obviously. Polymerization continues through the life of most plastics. Since in this case this is more prominent on the surface my best guess is it is accelerated by UV and possible oxidizers like ozone. Overpolymerized plastic becomes more hard and brittle and miniscule flakes seperate from the base. This by no means makes the tool of bad quality. Try to compare it with east imported garbage. It's just another company desicion that doesn't bother me much. S.M.

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#6
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Re: What Kind of Plastic is This?

10/22/2021 9:24 PM

UV has killed a lot of my plastic stuff but the screwdrivers spend 99.9% of their life in the dark.

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#4

Re: What Kind of Plastic is This?

10/22/2021 8:49 PM

Thermosetting plastic, similar to Bakelite…

which oxidizes, like most material, as it ages…

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#7

Re: What Kind of Plastic is This?

10/22/2021 11:06 PM

It must be related to your climate and storage conditions. I have quite a few Craftsman screwdrivers that I bought in the early to mid '60s. The handles of one or two that were not stored in the dark have "yellowed" somewhat, but the rest still look pretty much as they did when new, although of course scratched up from use.

Of course here in the Northern California Foothills, it's vastly drier most of the year than it is in Florida. Humidity values in the teens are common here, and single digits aren't rare.

Have you tried literally washing them? or even tasting them? Perhaps it's salt!

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#8
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Re: What Kind of Plastic is This?

10/23/2021 1:13 AM

"It must be related to your climate and storage conditions."
Yes. Hydrolysis may be your enemy.

Many CA cellulose acetate and CAB cellulose acetate butyrate objects contain plasticisers (often phthalates) which can migrate from the polymer structure and acetate groups that can react to produce acetic acid. Migration of plasticisers to the polymer surface can produce an acidic environment and warping of the plastic whereas hydrolysis of the acetate groups produces acetic acid and a characteristic vinegar-like smell.

If CAB cellulose acetate butyrate is the polymer, it will smell more like rancid butter as it degrades. The presence of bubbles or crystals (plasticiser) on the surface of an object or a mild vinegary smell is an indication that active degradation has commenced.

The degree of butyrylation of commercial CABs commonly ranges from 17% to 52% and will affect the long term stability. A large volume of work has been undertaken on the long term stability of CAB, as it is used in the storage of prepared uranium and plutonium reference samples. Screwdriver makers please take note.

Mark Bingham
fluoroplastics.com

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#10
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Re: What Kind of Plastic is This?

10/23/2021 7:49 PM

Very interesting. Thank you.

Over the years I have noticed the different smells on some screwdrivers.

Some of the smaller screwdrivers, an old Archer (Radio Shack) nut/screwdriver combo set comes to mind, had a strong somewhat vinegar smell and would become so brittle that they easily broke apart.

The Craftsman screwdrivers have a more mild smell that is harder to describe. All of the "action" seems to be limited to the surface. The white substance scrapes off very easily and the screwdriver seems 100% visually and mechanically good after a minute of scraping.

Only one problem. Do I dare let people know that I am excited that I now understand why my tool box smells?

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#11
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Re: What Kind of Plastic is This?

10/24/2021 2:10 AM

Very interesting - thankyou.

My old draftsman's set squares had to be discarded ~10 years ago after warping and giving off an acetic acid smell. They were originally my dad's, so were at least 50 years old at the time (possibly much older).

I'm not sure, but suspect the acetic acid may have started a chain reaction with my WILD drawing instruments case (black crinkle/crackle paint over diecast IMO) beginning to corrode. I only had a look at them today after many years - at one point, I thought that the acetic acid smell was emanating from the instruments, but it appears that they were bathing in an environment produced by the set squares. I assume some neutralising wipe down would slow/stop the corrosion (maybe a restoration project coming up) - any thoughts anyone?

Also a salutary warning!

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#13
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Re: What Kind of Plastic is This?

10/25/2021 6:24 AM

I dug an old set of drawing instruments out of the attic earlier in the year. The case was foam lined plastic & the foam had disintegrated & become sticky so that it glued itself to the instruments. A complete mess.

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#14
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Re: What Kind of Plastic is This?

10/25/2021 7:10 AM

Bad luck!

Thankfully, mine are still resplendent on the inside - I'd hate to lose them.

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#15
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Re: What Kind of Plastic is This?

10/25/2021 7:16 AM

Mine survived but took a lot of cleaning.

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#16
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Re: What Kind of Plastic is This?

10/25/2021 3:52 PM

Fortunately, mine were/are in cases with velvet linings, so no problem, But I started using CAD over 30 years ago, so the only reason for keeping them is nostalgia!

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#17
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Re: What Kind of Plastic is This?

10/25/2021 5:39 PM

I started cad about the same time,.but even though we started out with Drafting tables, to understand fundamentals… descriptive geometry, and finding points on irregular shape.

I’d think it would be hard doing that on CAD at the time. It was a 2 credit course… while calculus or physics was a 4 credit. Descriptive geometry was one of my hardest classes, and I’m glad I took it.

I had staedtler mechanical pencils and drafting tools…

I wish I knew what happened to them.

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#19
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Re: What Kind of Plastic is This?

10/26/2021 4:12 AM

Same for me, I still have drawing instruments, squares, french curves, ink pens, stencils etc. with no purpose now.

One item I bought years ago & have never used in anger is described as an architect's drafting set. It is a leather case slightly larger than A4. It opens to reveal a pouch for paper, a drawing surface & a small parallel motion drawing machine with square arms on a rotary head. There are also some templates which fit into the arms.

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#20
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Re: What Kind of Plastic is This?

10/26/2021 7:02 AM

For me, the best tool I bought when I was going to college was a circleometer… interesting that they didn’t change their packaging in 35 years… I guess after 35 years it’s still a whole new way to draw circles.

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#25
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Re: What Kind of Plastic is This?

10/26/2021 8:05 PM

I think I have a circleometer residing in my desk drawer. Haven't used it in years, and the last time wasn't for drafting! Might have been for marking gaskets for cutting.

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#26
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Re: What Kind of Plastic is This?

10/26/2021 8:17 PM

Oh,… that a good use… I like it,

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#21
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Re: What Kind of Plastic is This?

10/26/2021 10:47 AM

" it will smell more like rancid butter " ... Wow, that's pretty specific!

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#23
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Re: What Kind of Plastic is This?

10/26/2021 6:38 PM

That's right, because there is chemical relationship, that's where the root- butyr-- comes from (Greek/Latin words for cow).

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#9

Re: What Kind of Plastic is This?

10/23/2021 7:34 PM

I've noticed that too. but I just assumed it was something like mildew, and went on--don't even remember if I wiped it off. I've had them probably over 50 years, and they are usually inside a dark garage with humidity that is whatever the weather is doing.

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#12

Re: What Kind of Plastic is This?

10/24/2021 2:16 AM

Could also relate to what was on your hands last time you handled the screwdrivers. The effect also looks similar to "bloom" from things like superglue. Maybe you were handling some level of solvents that has caused this bloom.

To me it looks like contact based, since there are some areas of the screwdriver handles that seem totally unaffected. (Unless you already wiped those down.)

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#22

Re: What Kind of Plastic is This?

10/26/2021 5:43 PM

"Causes of Plastic Oxidation

Chemicals in plastic react with oxygen in the air. The oxidation of plastics leads to degradation. Plastics become physically abraded or are subject to sunlight, air pollution, moisture, high temperature and biological exposure. Ultraviolet B radiation (UVB) breaks down plastics via photo-oxidation. Eventually this leads to brittle, cracking plastic. While more modern plastics contain stabilizing additives, older plastics may not, and suffer more risk of degradation. In the case of ebonite, which contains sulfur compounds, reaction with oxygen occurs and eventually water as well, ultimately leading to sulfuric acid production. Storing some plastics, particularly museum pieces, in an oxygen-free area may be warranted. There are oxygen-absorbing products that seal plastics. Additionally, reducing exposure of plastic to sunlight can stave off photo-oxidation. In most cases, however, these steps are impractical, especially for outdoor items. In that situation, some methods exist to help restore plastic surfaces.

Plastic Restoration Methods

Many oxidized plastics can be restored at home. The surface needing restoration should be washed gently and rinsed thoroughly before proceeding. For highly valuable and museum pieces, expert restoration is advised."

https://sciencing.com/tips-getting-rust-off-repainting-wrought-iron-gazebo-12089846.html

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#24
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Re: What Kind of Plastic is This?

10/26/2021 7:27 PM

Plastics are chemicals. They do contain additives usually at micro (vitamin) level, e.g., for color or to protect against unusual service conditions like continued sunlight as noted above. Most plastics are remarkably moisture-resistant, and in their stable polymerized form comprise the vast majority of today's uses. Biodegradables add reaction products in their not-so-harmless trip to water and CO2. The plastiphobes have convinced people that plastics last forever yet still degrade to "chemicals."

Ebonite was well-known for a century, especially for bowling balls, but it is a sulfur-cured rubber and not a conventional plastic at all.

Plastics are not a homogeneous "they." They vary in structure and are basically inert in normal conditions and not toxic, despite the fear of chemicals that drives people to want to see them so. In this case of screwdriver handles, moist but dark, the handles may be old CA or CAB with plasticizer exuding (oxidation unlikely especially if wiped off so easily), or if new, from an unknown and uncontrolled source. It has little connection with today's plastics industry.

Museum pieces do need special care, but it's the oils in oil painting that have driven conservation work, with oxygen-barrier plastics available if needed, and well-developed for cheese and soft drinks (oxygen and CO2 resistance go together).

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