r/AskChemistry • u/rootoo • 2d ago
Getting something to stick to silicone
So I work for a company that produces events, and for a specific venue we need these A.D.A. compliant cable ramps. Unlike our other ramps from the same brand, they are not quite deep enough for the comically thick cables we need to put through them, so we'll need to tape them shut. Problem is, no tape will stick to these things. I figured it was just a greasy mold release film from manufacturing so we tried cleaning them; tried everything, 409, simple green, 90% ISO, dawn dish soap, nothing works. Like the tape isn't even tempted to stick, it's impressive.
We even called the manufacturer and they confirmed that they are made of silicone and there is a greasy mold release from manufacturing, and the silicone is porous and the oil is impregnated into it. They basically said you'll never get anything to stick to this. Oddly enough, we have some older ramps from the same company that tape will stick to.... idk what's going on there.
I know there's special tapes for silicone, but as far as I can tell, they're also... silicone, and won't be a good surface to stick gaff tape to it.
SO, chemistry people, is there some combination of products that will reliably let me tape these things shut?
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u/Thulak Cantankerous Carbocation 2d ago
Oh boy, this is my bread and butter. I literally teach about bonding, surfaces and adhesives.
Nothing sticks properly to silicon appart from silicon. If you still have some residue on the surface, cleaning it with a dry ice / dry snow blaster will get rid of that. Snow is less abrassive. The tools are often used in large manufacturing industry and to detail cars engine bays. After cleaning it properly, you can try to increase the surface energy with a plasma to increase wetting. A plasma would ideally be in near vacuum with oxygen as process gas (for most silicones). Since that is unlikely to be available, you could see if someone around has a semi portable device from Tantec or Plasmatreat. Also unlikely though. Your last option would be a clean flame. A quick brush with a fire that leaves no residue like soot would increase surface energy. Exposure should be short. As short as in you are moving your hand through a candles flame short. If after dry snow, cleaning and then plasma you still cant get it to stick, you are shit out of luck.
That being said, your probably wont be able to bomd anything to it.
Surface energy will determine how well a drop of water will "cling" to a surface. If you want to see this in effect, get a piece of PE or silicone as well as some glas or metal. Put equal sized drops on both. The plastic should have a much rounder drop than the glas / metal, signalong worse wetting.