deskthority

As I work through elecplus's warehouse inventory, I find myself posed with an interesting question: what is the best way to clean many thousands of key caps?

Among other things, I like to have, at least, a basic understanding of the chemistry going on before I risk putting rare, high value items through a process that might damage them. What I call the "Chemical Marketing Companies" are loathe to let on precisely what is in their formulations. It often takes some real effort to discover key ingredients, and the formulations are often more simple than one might imagine.

Incidentally, MrsXMIT and I were looking into laundry detergents. Again, frustrated by the confusing copy and offensive artificial odors of various detergents offered by Chemical Marketing Companies, we started sleuthing. It seems like oxidizers with enzymatic cleaners were the way to go.

Before we begin, let me be clear: I'm not a chemist! So, if, say, a fellow keyboard enthusiast with a PhD in Chemistry or Chemical Engineering would like to correct me, please do. (Paging Chyros.)

Let's start with the beloved stalwart of key cap cleaning, the denture tab. These popular little pucks are cheap, easy to obtain, easy to store, do a reasonable job alone when dropped into warm water, and leave key caps smelling minty fresh. No wonder they're so popular!
But, don't eat them, lest you end up a case study in the Journal of Medical Toxicology!

https://www.researchgate.net/profile/Da ... rforation/

From the article,

Pfizer, the manufacturer of Efferdent, lists the ingredients in alphabetical order:

Blue #2, ethylenediaminetetraacetic acid (EDTA), FD&C Green #3, flavor,
polytetrafloroethylene (Teflon, DuPont), potassium monopersulfate,
sodium bicarbonate, sodium lauryl sulfoacetate, sodium perborate monohydrate,
sodium saccharine, sodium sulfate, and sodium tripolyphosphate anhydrous.

The product has a pH of 9.5, weighs 2.1g/tablet, and has a titratable O2 of 129-162mg/tablet (Personal communication with Pfizer Products Hotline, 2005). The Material Safety Data Sheet (MSDS) for Efferdent tells us that it is 48% sodium perborate monohydrate, 21% potassium monopersulfate, 20% EDTA, and 11% “non-regulated/non-hazardous ingredients”.

I'm not terribly thrilled at the presence of artificial flavor or artificial color. We don't need them. But apart from this, what's in here?

ethylenediaminetetraacetic acid - chelating agent, grabs metal ions.
potassium monopersulfate - oxidizer
sodium bicarbonate - mild disinfectant, pH balance
sodium lauryl sulfoacetate - wetting agent?
sodium perborate monohydrate - bleach, decomposes into hydrogen peroxide and borate

...and a bunch of other stuff, including perhaps something I missed.

I don't really think this will do any harm. I'm not thrilled about the sulphur chemistry because I don't quite understand it, there are a lot of sulfates in there. If you have a sulfate allergy you should be careful around the stuff.

Curious, I set out to do a little comparison. I purchased an off the shelf "Ultrasonic General Purpose Cleaning Powder".
This one had a much simpler ingredients list: sodium carbonate, sodium metasilicate, trisodium phosphate. It reads like a laundry detergent from the '60s.

But that also read like the ingredient list of the stuff we use for our dishes: Seventh Generation Dishwasher Detergent Powder, Free & Clear.

https://www.seventhgeneration.com/dishw ... -detergent
The ingredients list is provided front and center on the product Web page.

Ingredients:
Sodium chloride (mineral-based processing aid),
sodium sulfate (mineral-based processing aid),
sodium carbonate (mineral-based cleaning agent),
citric acid (plant-derived water softener),
sodium percarbonate (mineral-based oxygen stain removal agent),
ppg-10-laureth-7 (plant-modified synthetic cleaning agent),
sodium silicate (mineral-based cleaning enhancer),
sodium polyaspartate (synthetic anti-filming agent),
protease enzyme blend (plant-based soil remover),
amylase enzyme blend (plant-based soil remover).

So, soap, peroxide bleach, more soap, and some enzymatic cleaners. No sulfates. Of course, no colors or fragrances. Reasonably easy to find here in the US.

To date, our results using this dish detergent with key caps have been great. It will clean all but the truly filthiest of key caps with tar or heavily oiled grease, which then need a cursory wipe afterwards.

The real motivation for this is that it scales much better. There is less paper waste and less work when cleaning a truly huge batch of key caps...
We set them to soak overnight, drain them, rinse them, then do a final rinse by bringing them through three buckets of the cleanest water you can find: distilled, deionized, or reverse osmosis. This last step is critical for removing any possible lime scale.
Then, we set them to dry on drying racks overnight, with a fan and a dehumidifier running.
So far, so good.

I'll continue to use denture tabs for small batches or for cleaning key caps at friends' houses, but for boards destined for resale or for these epic batches of keys we've had, I'll prefer this dishwasher detergent.

What are your thoughts? Please comment below! Thanks for reading.

I’m mainly thinking about whether that’s a F107 on the yellow-lidded tote behind the Home Depot buckets and if it would like a nice desk to live on...

I’ve had lots of success with dish gel (for hand washing - not dishwasher) and water in an ultrasonic machine. Good rinse, then a wipe down to dry and remove any loosened dirt that didn’t fall off. Clearly doesn’t work at scale though.

I would be careful with hand washing gel or anything that suds.

I have a friend whose parent, at the time, worked for a large Chemical Marketing Company. Though they offered many consumer-grade soaps with names you would likely recognize, they all had one of two base formulas. They were, internally, referred to as either "silky soft" or "squeaky clean". Which one would you want for your key caps?

The F107 is not for sale. It is in a queue for cleaning hence its current location.

My preference is definitely powdered laundry detergent.

I am not a chemist either, although my daughter just graduated from college with a degree in chemistry. Unfortunately, she has very little real-world understanding of the facts that she learned.

Before my kids were born, I just used any old ordinary laundry detergent, but my wife convinced me to look for a better alternative for tender baby skin.

I settled on "Charlie's" which can be found at places like Whole Foods where it looks expensive but it goes a long way. I eventually added added "Biz" or similar enzyme helper. I mix about 4 parts detergent to 1 part booster and use less than the recommended amount for a load. And double rinse. This makes for soft, well-cleaned clothes with no scent. And it causes very little fading or wear. I eschew fabric softeners like the plague.

For keyboard keys I use the same formula, a scant teaspoon in a couple of liters of hot water is plenty for a set. Soaking for 10-20 minutes is plenty. Be sure to rinse well. On rare occasions there is something stubborn like adhesive residue that has to be handled individually.

XMIT wrote: 18 Apr 2021, 15:39 They were, internally, referred to as either "silky soft" or "squeaky clean". Which one would you want for your key caps?

Neither. That’s great feedback. I’ll give your method a try next time around.

I've never seen a batch like this. My process is very time consuming since I only do one board at a time for my own personal collection. I just use warm water and liquid dish detergent. I sonic clean or even wash each individual key by hand with a cloth dish rag after soaking in warm water. I should probably rinse with distilled water like you mentioned. I always use an air blower meant for cleaning computers to immediately remove any excess water.

[Edit] Also one downside I see to this method is that the original keys do not end up with the same board. Why is this important might you ask? Dye sub printing varies from board to board! I look for these subtle details. If I have a board missing a key I try my best to find a suitable replacement to best match the surrounding keys which can be very hard to do. It looks like this batch is just for the stems and spacebars so perhaps you are scaling up your process where it makes the most sense.

I have a different method for small batches. The ultrasonic cleaner can do one keyboard's worth of caps at a time. I've started drying my keys on the shelves of a dehydrator, the sort of thing you might use for making beef jerky. It provides a steady stream of warm dry air and gets all the water out in about an hour. I'll detail that method some more when I start running more things through that pipeline.

I really wanted this post to focus on the detergents used, and here we are talking process. So it goes.

When it comes to replacing individual keys, we are often replacing a single key on a board. Say it's the 'E' key. We'll cherry-pick the best matching 'E' key for the particular board. It's an informal, visual process.

I actually used a dishwasher for my XT (it was _very_ dirty).
The result was great, except the comma key ended up touching the heating element and buned off one of the corners.

I've been using Alconox, a commercial powdered dish soap, mostly used by restaurants. No colors, no odors, haven't looked at the list of ingredients but it has worked well using a rag or toothbrush and a pan of hot water. Dip the brush or rag into the water, then into a cup of the soap powder, gently scrub several caps and repeat. Rinse the caps and let them air dry overnight. Takes about an hour for one keyboard's worth. So far no issues, no scale or residue. Won't help with yellowing, of course.

Polecat wrote: 28 Apr 2021, 04:35 Won't help with yellowing, of course.

Sodium percarbonate is the active ingredient in "Oxi Clean" type products. It is sodium carbonate that releases a peroxide. I believe it is used somewhat commonly by home brewers to clean their equipment. You might experiment with adding small amounts of that, it may help with yellowing.

XMIT wrote: 28 Apr 2021, 04:45

Polecat wrote: 28 Apr 2021, 04:35 Won't help with yellowing, of course.

Sodium percarbonate is the active ingredient in "Oxi Clean" type products. It is sodium carbonate that releases a peroxide. I believe it is used somewhat commonly by home brewers to clean their equipment. You might experiment with adding small amounts of that, it may help with yellowing.

Thanks for the tip, I'll look into that.

I might just try the 7th Generation powder. The liquid didn't do very much for me. Simple Green was better. I'm still pretty happy with how Efferdent works and how little it costs, although I think I'll get some of the "heavy stain" version the next time I use it.

Thanks for posting!