Ultrasonic Key Cap Cleaning - 2021 Edition

[XMIT]

We get a fair number of keyboards - particularly IBM buckling spring boards of late - through XMIT Labs. As always, we're looking for the easiest and best ways of cleaning key caps.

We've already talked about soap recently. See viewtopic.php?f=7&t=25639.

Today we're here to talk about how we clean a pipeline of key caps. This can scale down to a single keyboard but works best when you need to keep things moving.

Ingredients:
Ultrasonic cleaner with cleaning basket.
Salad spinner.
About three gallons or 12 liters of water, reverse osmosis, deionized, or distilled.
Two buckets, at least 2 gallons or 8 liters each. A gallon or 4L of water goes into each bucket.
Food dehydrator

First, run key caps through the ultrasonic cleaner in the usual fashion. For PBT key caps I turn on the heat and run them for about 15 minutes total. I gently agitate a few times to help get some of the dirt moving.

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Dump them out into the salad spinner:

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, and spin dry. The dirty water goes back in the cleaner - even with this level of dirt it does an excellent job cleaning.

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The key caps go through a rinsing pipeline: first in one bucket, then spin dry. Water goes in the first bucket, key caps in the second.

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When transferring key caps to the second (cleaner) bucket, dump the water from the spin dry back into the first bucket.

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Repeat: remove key caps from second bucket, spin dry, return water to second bucket.

The real trick is drying! I struggled to find a solution for years. After all, the undersides of buckling spring and Cherry MX key caps have plenty of places where water can hide, eventually ruining springs. We need to get the keys completely dry. But how? I used to use a fan, towels, and time, lots of time.

But, then it hit me: food dehydrator.

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Each tray holds about one ultrasonic cleaner load of key caps. Perfect!

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Key caps take an hour or so to dry. By the time the racks are full, we can loop back around and start pulling dried key caps from the dryer, keeping the chain going.

How are you cleaning key caps in 2021? Any other brilliant ideas out there?

[TNT]

Haha, this is some professional-level stuff. I use soapy water with dental cleaning pellet and let them dry by just leaving em out in the open

Good ultrasonic cleaners are quite expensive and not really worth it for me, but the food dehydrator idea looks promising. Might look into that.

[ifohancroft]

That's a brilliant idea! Thank you!

Can you recommend a specific brand and model of ultrasonic cleaner and a food dehydrator?

P.S. Does running the keycaps through the food dehydrator cause any change in the durability of the plastic?

[clickykeyboards]

Thanks for the recommendation on the dehydrator. Timer and temperature control look like great features.

It is important that when ultrasonic cleaning or water submersion of the model M key stems to get out all the water removed from all the points where the plastic and metal are in contact.

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I have seen too many cases of previous owners who followed an urban myth and "washed" their model M keyboards literally inside a kitchen dishwasher. While it might clean the external surfaces, there are many internal crevices where water will infiltrate and rust is inevitable. (Then requiring a complete teardown, conductive circuit-layer replacement, buckling-spring replacement, bolt mod to reassemble and save the model M keyboard from the landfill).

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[XMIT]

Can you recommend a specific brand and model of ultrasonic cleaner and a food dehydrator?

P.S. Does running the keycaps through the food dehydrator cause any change in the durability of the plastic?

I'll post links a little later but they may be specific to the US.

The dehydrator runs at about 60 C which is well below any temperature that can harm PBT plastics. If you were to leave them at this temperature for weeks on end it's possible the dye sublimated legends would start to bleed. I've not seen that with this drying setup.

[ifohancroft]

I'll post links a little later but they may be specific to the US.

Thank you!

The dehydrator runs at about 60 C which is well below any temperature that can harm PBT plastics. If you were to leave them at this temperature for weeks on end it's possible the dye sublimated legends would start to bleed. I've not seen that with this drying setup.

My concern was mostly about the dehydrator removing any natural moisture there may be in the plastic itself but not that I think about it, but now that I think about it, there's probably no such thing and also, like you said, at 60 C there won't be any problem for a short period of time.

[XMIT]

Cleaner: https://www.amazon.com/dp/B00HLBKNKI/
Dehydrator: https://www.amazon.com/dp/B07Y2ZKX6Y

[inmbolmie]

Oh my, now I urgently need to purchase just another kitchen appliance... Thanks for the tip!

[vvp]

Ultrasonic cleaner is fine and useful but you do not need dehydrator. Keycaps can dry themselves on a piece of cloth or directly on the keyboard. I just dump them from the cleaner on a piece of cloth and start putting them directly onto the keyboard blowing on the underside of each cap to get any bigger water droplets out. They will dry themselves by the time I will have seated them all on the keyboard.
There is not enough water on a keycap to influence the keyboard after blowing out the excess water from the keycap underside. It is enough to blow with your mouth.

[XMIT]

I just dump them from the cleaner on a piece of cloth and start putting them directly onto the keyboard blowing on the underside of each cap to get any bigger water droplets out. They will dry themselves by the time I will have seated them all on the keyboard.

There is not enough water on a keycap to influence the keyboard after blowing out the excess water from the keycap underside. It is enough to blow with your mouth.

Doing any operation per keycap does not scale when you have tens of thousands of keycaps. I was going to say thousands but you get there pretty quickly with just ten keyboards.

There is error involved in your approach as well as cognitive load. For personal keyboards maybe this is fine. For commercial keyboard sales or repairs the standard is zero water.

It's not about the influence on key feel. It's about the fact that even a trace amount of water, with nowhere to go, will corrode galvanized steel springs.

We're in the middle of a global pandemic, I don't want to explain to customers that I'm blowing, with my mouth, into a confined space of their item.

The dehydrator is about 10-30x faster than towel drying in my experience. I can put the key caps on a towel, put that towel on a wire rack, and point a table fan at it. That does work really well and gets the key caps as dry as they dryer might. However it does take about overnight to get all key caps dry to my satisfaction, which, again, is: zero droplets of water.

I'm not telling you how to clean your key caps, but I am telling you how and why I do what I do.

[vvp]

If you want to do it commercially for people who sent you a bag of keycaps and receive back a bag of cleaned keycaps then your approach is fine. But dehydrator does not make sense for people who clean their keyboards from time to time.

The biggest amount of work is not cleaning or drying. Even when one adds "cognitive load" of blowing. The biggest amount of work is in removing keycaps from a keyboard and putting them back onto it. A blow to keycap underside and even wiping outer sides of a keycap is hardly any additional work when seating keycaps back onto a keyboard. On the other side you save all the work with dehydrator and maintaining one more device at home.

Trace amounts of water will evaporated from a keycap very quickly. It will not corrode anything. It will not get into contact with springs or contacts(*). At most it will be on the plastic switch stem for a little bit of time while it evaporates. Any bigger water droplets are already blown away from the keycap underside.

(*) Well, maybe you hae some switches which have metal parts directly touching keycaps. You have some point in such a case.

[XMIT]

But dehydrator does not make sense for people who clean their keyboards from time to time.

It has saved me quite a lot of effort already. One may already be present in the kitchen. There was a time when these were a common $5 thrift store item.

Trace amounts of water will evaporated from a keycap very quickly. It will not corrode anything. It will not get into contact with springs or contacts [...] Well, maybe you have some switches which have metal parts directly touching keycaps. You have some point in such a case.

This post was directed squarely at buckling spring (IBM Model F and Model M and similar e.g. AT&T) key caps, which are a worst case in several ways. They have an area with a very high surface area to volume ratio on the underside of the key cap where water tends to collect and is difficult to see. They have two piece caps with an area between the cap sections that can wick and store water if not split. If split, there are double the key caps to dry. Plus, there are several readily exposed and minimally protected steel pieces - springs and plate - inside the case. clickykeyboards' post showed this pretty clearly.

But, sure, if it's just one set of Cherry MX key caps, then a bowl, warm water, a denture tab, a couple of pinches of dishwasher soap, and some towels will do the trick.

[Bjerrk]

Cool idea with the dehydrator!
I do not really care too much if it is "worth it" to most users - after all, the vast majority of the population would argue that repairing old keyboards isn't "worth it" either

Now I feel a tinge of guilt towards my buckling springs. Did I clean those keycaps properly? Are you slowly corroding away, my beloved springs?

[vvp]

Ultrasonic cleaner is worth it, and not only for (cherry) keycaps. I have one myself. It was a good buy.

[hellothere]

I have the slightly cheaper version of the ultrasonic cleaner mentioned and I will +1 that it's been pretty reliable. That being said, the middle of the 3 number LEDs burnt out in about a week. However, I know that 0x0 = 90 seconds, etc. I almost always use 4x0 = 480 seconds. I've done several thousand complete key switch assemblies in the past two-ish years I've had it. I think I only paid $65 or so. I think I got it through Walmart.com.

Regarding the dehydrator, I think it's a cool idea. I don't have the volume of KBs to need one ... and I live somewhere where the relative humidity is often under 10% . However, I've been stealing the silica gel "do not eat" packs out of various medications (after the medication has been used, of course). I can throw a bunch of wet items into a plastic colander, toss in some silica packs, and leave that out on the back porch -- but out of direct sunlight -- to dry. Works great. Rarely takes even a day to dry.

[TNT]

Decided to get an ultrasonic cleaner too, since I got some Microswitch caps that are very dirty even on their insides. Denture tabs don't do anything and I can't reach in there all the way by hand. Found a used one in good condition on eBay, so I didn't even pay that much. Plus I can use it to just heat my water up to and hold it at a certain temperature without cleaning, so it'll definitely save me some time in the long run.