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 Post subject: KNOBS and the deterioration thereof.....
PostPosted: Apr Sun 11, 2021 4:06 pm 
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Greetings. I am emptying some of the old oak drawer units full of knobs, which I acquired, and a lot of them are showing moderate to severe "milky spore disease" … LOL ...the white stuff that leaches to the surface of old plastic knobs when they break down or whatever the exact chemical process is.

My question to the forum … is it even worth keeping these? Can they ever be recovered/restored to their original beauty? There are hundreds, if not thousands, showing this kind of breakdown.

Just a preliminary sorting question … exact determination as to what to keep or not keep can come later.

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Sun 11, 2021 4:18 pm 
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There is no sealant to prevent the eventual deterioration of that type of plastic.

Ideally, taking mold castings or in some way 3D scanning to at least preserve the dimensional information once the last one in good condition crumbles.

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Sun 11, 2021 4:58 pm 
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Barry, if you are talking that white waxy crud that they get, like Xcellite driver handles, It does clean off nicely with some work. Fingernail and/or a wooden spudger used gently will often remove that stuff (Yes, yes, it will eventually come back). So, if you don't wish to keep cleaning or owning them, heck, put lots up in the Classified section. But don't toss them into the bin (I didn't really think you would :wink: ).

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Sun 11, 2021 5:16 pm 
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Thanks! I pretty much figured as much. No Don, no tossing into the bin... next Estes auction maybe lol. If I had my act together they'd be in $1 ziplock bags at Kutztown, but I can't get it together for this coming one. Perhaps the next. Or my open house......eventually.

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Sun 11, 2021 6:25 pm 
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I read that washing in oxyclean and or vinegar will help. I think It’s some sort of mold? That reminds me that I’ve got a screwdriver that this is happening to. I washed it off with WD-40 a while back, but the white fuzz returned. Will try vinegar, and if that doesn’t work, will try oxyclean. Chlorine bleach seems a little hard on things so maybe not a good idea.

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Sun 11, 2021 6:42 pm 
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I have no oxyclean, but vinegar is plentiful. Soaked screwdriver in a glass of ordinary white vinegar for a few minutes. Scrubbed lightly with a toothbrush, crud gone. Rinsed well. The problem with molds is that once they’re in your environment, they will grow if moisture conditions are correct, and they have a food source. And they sometimes send spores deep into things.

What’s the humidity like where these knobs are stored?

If you want to treat the drawers they’re stored in, you could try making up a spray of borates mixed with water. There’s a product called Tim-bore and another called boracare. One is pre mixed with ethylene glycol, the other is a dry powder you mix with water. They are insecticides, and also used to prevent mold and dry rot in wood products. Might want to treat the drawers with that to kill the spores. Or just fix any humidity issues to keep everything dry enough that mold won’t be able to grow.

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Last edited by anchorman on Apr Sun 11, 2021 6:46 pm, edited 1 time in total.

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Sun 11, 2021 6:44 pm 
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If you do vinegar, consider a mild solution of baking soda and water to neutralize the remaining vinegar that may creep in between plastic and metal joints on the knobs.

Ultrasonic cleaner with vinegar or oxyclean would probably work wonders, but i’d Want to try a few samples of various knobs to make sure they don’t deteriorate in the ultrasonic cleaning machine.

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Sun 11, 2021 7:39 pm 
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anchorman wrote:
...
Ultrasonic cleaner with vinegar or oxyclean would probably work wonders, but i’d Want to try a few samples of various knobs to make sure they don’t deteriorate in the ultrasonic cleaning machine.


I just got an ultrasonic cleaner and have not used it yet. Heck, that may be the first run...

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Sun 11, 2021 9:08 pm 
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anchorman wrote:

What’s the humidity like where these knobs are stored?

Good question. I have plastic knobs accumulated since the '50's, with none of what you all are talking about. I'm guessing that the dry climate here prevents that mold from occurring.

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Sun 11, 2021 11:01 pm 
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fifties wrote:
anchorman wrote:

What’s the humidity like where these knobs are stored?

Good question. I have plastic knobs accumulated since the '50's, with none of what you all are talking about. I'm guessing that the dry climate here prevents that mold from occurring.


This is why I’m pretty convinced it’s mold, and not the plastic deteriorating spontaneously. Usually that involves crumbling and such, or turning to goo in women cases. I once thought the white stuff was leaching out of the plastic, but I can’t think of what it would be, other than mold growing on it.

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Mon 12, 2021 12:29 am 
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chemical reaction between the plastic content of the knobs.

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Mon 12, 2021 1:14 am 
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The humidity of the storage area was pretty high... Gary's basement mostly. But I don't think it's mold. Regardless I'm not doing anything about it at the moment... just still working on bulk pre-sorting and freeing up floor space.... which includes selling what has turned out to be a specatular assortment of old oak library file drawers, flat storage drawers, magazine drawers.

Oddly I have always wanted one of these drawer units..the old oak library card file stacks... and now that I have several, I've decided I really don't need one. Oh well.

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Mon 12, 2021 2:31 pm 
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I sprayed some knobs with LA's Awesome Cleaner (from a dollar store) and it cleaned the white crud quickly, it has not returned after several years.

My Craftsman 1/4" driver handle smelled like vomit, so I just replaced it with a Crescent that has an easy to grip three-side handle https://www.amazon.com/gp/product/B079TPC85J


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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Mon 12, 2021 7:29 pm 
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Location: Kingston Ontario
Can you post a picture of that LA'S Awesome Cleaner from the dollar store. I live in Canadas so don't now if can buy here.


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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Mon 12, 2021 11:06 pm 
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bruce47 wrote:
Can you post a picture of that LA'S Awesome Cleaner from the dollar store. I live in Canadas so don't now if can buy here.


There are three Dollar Tree stores in Kingston, Ontario to try https://www.dollartreecanada.com/store-locator/

This is a picture of Awesome Cleaner, the yellow version I used http://www.lastotallyawesome.com/shop/a ... aner-32oz/

Don't order from mail-order, it will be damaged and leak in shipment, and the odor is intense.


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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Tue 13, 2021 5:24 pm 
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Location: Auburn, AL
Barry H Bennett wrote:
The humidity of the storage area was pretty high... Gary's basement mostly. But I don't think it's mold. Regardless I'm not doing anything about it at the moment... just still working on bulk pre-sorting and freeing up floor space.... which includes selling what has turned out to be a specatular assortment of old oak library file drawers, flat storage drawers, magazine drawers.

Oddly I have always wanted one of these drawer units..the old oak library card file stacks... and now that I have several, I've decided I really don't need one. Oh well.


mold loves damp. even if it's not mold, and some some decomposition product of the plastic, it's accelerated by moisture. People say it's a decomposition product of the plastic CAB (cellulose acetate butyrate), but none of the other armchair internet theorists has any explanation as to the chemical/physical mechanism of the deterioration. I'm going with the mold hypothesis, since people have had good luck halting it with vinegar (kills most molds), and also just due to how it looks and spreads in patches on the surface most of the time. Molds will grow on pretty much everything if given the chance.

I found after soaking a particularly bad screwdriver handle the other day in vinegar, the stuff came right off. we'll see how quickly it comes back.

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Tue 13, 2021 5:30 pm 
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Wish I were in a position to buy some of those drawer units. I love them, can never have enough!

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Tue 13, 2021 6:53 pm 
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but none of the other armchair internet theorists has any explanation as to the chemical/physical mechanism of the deterioration.
It takes a "wet" lab and a plastics chemist to describe the process of plastic deterioration...

One of the most destructive devices for plastics is Ultra-Violet exposure. The light breaks the long polymer chains into shorter ones and leaves bits to form a "non-compound" in between. In the ABS these bits have a different refractive property and cause the plastic to yellow and become brittle.

Other mechanisms are more complex, usually it is a bad alloy of the plastic to begin with. It was not specifically designed for longevity but be cheap, easy to mold into attractive shapes... The plastic alloys may have not been precisely mixed, therefore, some products may withstand the test of time better than others. The same applies to rubber products, we have all seen rubber covered wire, some has turned to goo, other into crumbs. That has a chemistry issue, too much or too little curative and well as the type/color of the filler affects longevity. As we have seen some wire FWIR the green, tends to remain supple despite being 80 years old.

Too bad this "problem" did not come up before I retired. The plastics wet lab was the next room over from my former electronics lab. I would be there routinely to repair some of their ancient analytical equipment.

There is no "magic" liquid as yet known to permanently make the "rot" stop. Just like there is no stopping pot metal from expanding and crumbling over the years.

As I stated, taking castings or 3D scanning of good examples may help to at least preserve the appearance of a replica knob for the future.

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Tue 13, 2021 7:58 pm 
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I get that UV breaks down the polymers, but I don't see why that would cause moldy looking stuff to initially form selectively on the surface of some plastics like that, and then spread over the whole thing. molds due tend to form patches, though, and spread from there. Wipe the moldy looking stuff off, and it looks good as new underneath, at least on the CAB screwdriver handles. I've yet to have one fall apart from whatever deterioration it was experiencing, and I've got some pretty old screwdrivers. deterioration from plastic decomposing due to purely atmospheric or light issues tends to be more uniform.

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 Post subject: Re: KNOBS and the deterioration thereof.....
PostPosted: Apr Tue 13, 2021 9:13 pm 
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Thank you BikenSwim.
I got a bottle.


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