Never forget that rubber bands eventually go bad.AND, if you need less-ephemeral, non-messy rubber bands, use silicone rubber bands (FREE ADVICE #002).

Fragments of deteriorated rubber bands. At upper left: bits from rubber bands that were, IIRC, bluish-green originally. Or were they purple? They're bluish-green now. At lower-right: parts of what were once white rubber bands. — Fragments of deteriorated rubber bands. At upper left: bits from rubber bands that were, IIRC, bluish-green originally. Or were they purple? They’re bluish-green now. At lower-right: parts of what were once white rubber bands.

Rubber bands (here taken to mean solid, non-woven elastic rings) degrade. Whether they’re made from natural rubber or synthetic rubber (e.g. nitrile) or polyurethane (like some shiny and clear or brightly-colorful elastic bands) or silicone, they will eventually break down and fail. Silicone rubber bands are, IMHO, the least terrible rubber band material because, in my experience, their failure mode is the least harmful of them all: they simply snap.

Recently, while rummaging through my stash of prototyping boards, I found to my dismay that a few short years ago I had foolishly used ordinary rubber bands to bundle some Bakelite prototyping boards together. The protoboards are all one-sided (i.e. they’ve got copper traces present on one face only), rectangular, and aside from a margin of solid Bakelite along every edge, are shot through with pin-sized holes spaced 2.54 mm apart. They were (and are once again) grouped by shape and size and the patterns of the copper traces.

I’d used some white rubber bands, some black rubber bands, and some rubber bands that were once blue-green or possibly purple but those latter-most rubber bands have turned dark blue-green now.

Two single-sided Bakelite prototyping boards, previously each the top or bottom PCB in a stack held together with a rubber band.

In the photo above, you can see two of these prototyping boards adorned with the fragmentary remains of one of these black rubber bands and one of the blue-green-maybe-purple rubber bands. I pried them apart moments before snapping this picture. The smaller board on the left was the bottom-most in its stack, held together with the blue-green band and the larger board was the top-most in its sheaf, wrapped with the black rubber band. The stack of smaller boards had rested on the stack of smaller boards and they had been in a bag full of other bundles of similar-but-different one-sided Bakelite protoboards. Time passed. A few short years later, I unearthed the plastic bag, began sorting through its contents, and found out that all of the rubber bands had rotted into uselessness.

Closer view of the surface of the larger board, showing how the blue-green rubber band (but not the black rubber band in this case, had oozed into the holes on the Bakelite-only rear side of the smaller prototyping board.

All of the black rubber bands went bad in one way and the blue-green ones went bad in another way. The black rubber bands turned gooey and melty at some point. They looked wet in some places and were sticky at the spots where they looked wet. The blue-green rubber bands dried out and got brittle without going goopy. Both seem to have retained their dimensions and stayed soft-ish rather than shrinking and brittle-izing into something resembling uncooked spaghetti.

Something the blue-green rubber bands did that the black ones didn’t was ooze or creep into the holes in the protoboards. See the bumps on the shreds of blue-green rubber band in the closeup, taken nearly edge-on, of the larger board? Each little protrusion matches up with one of the holes on the smaller board. Very slowly, that rubber band was flowing through the holes in these two protoboards. If you look closely at the image before last, you’ll see that those bits of blue-green rubber band that remained clinging to the smaller board when I pried them apart sport the same little nubbins.

Scraped the blue rubber band mostly but not completely off the traces side of the larger prototyping board.

My cleanup methodology consisted of scraping away the rubber band dregs and then using an ethanol-wetted wipe to rub off the remaining crumbs of elastic material, along with, I suspect, adsorbed air pollution and exudate from the surface of the aging Bakelite itself. Some of the holes were plugged with broken-off rubber band pseudopodia and I reamed them out using a mobile phone SIM card eject tool.

Clockwise from top left: post-scraping consecutive steps in the process of cleaning degraded rubber bands off one of these prototyping boards.

Some rubber band material residue continues to lurk inside these holes, Long their rims. I could probably eliminate these last vestiges of rubber band using a toothbrush wetted with ethanol, but I don’t think that what little stuff remains there would prevent me from making an acceptable solder joint. For now, I won’t fuss over those final specks.

In the bottom panel of the final image, you can see that the two-hole pads that had been encrusted in dismembered rotted rubber band material are scratched-up and shiny. That’s a consequence of the scraping step but it’s only superficial and the pads are still perfectly usable.

How I repacked these protoboards: each stack is wrapped with a silicone rubber band and, beneath it, a strip of thick-ish paper (cardstock) between the silicone and the Bakelite and copper.

All of the Bakelite prototyping boards got a thorough ethanol rubdown before being girded with strips of cardstock, around which I wrapped a silicone rubber band, and slipped into a clear ziplock bag. If I’d had the foresight to slip cardstock between the non-silicone rubber bands and the protoboards to begin with, the cardstock would have taken the hit from the disintegrating elastic.

An example of what a failed silicone rubber band looks like. — Silicone rubber bands seem to endure a *lot* longer than other sorts of rubber band, but I happened upon this snapped white silicone rubber band recently (July 2024) and snapped a photo so that I could add a real-world visual reference for silicone rubber bands’ failure mode to this post.

When they go bad, silicone rubber bands simply break, typically at their thinnest or weakest point, and don’t pose much of a cleanup problem, so why did I bother with the paper strips this time? Mostly, I’m hoping they’ll protect the silicone rubber bands from the sharp-ish edges of the Bakelite sheets because, absent some skinny section or a tiny divot somewhere along an edge of a silicone band, that’s the sort of place where one would likely eventually snap.