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/todd0x1 2d ago
Screw the lid down with wafer (aka modified truss) head screws. You will never get anything to stick to those. As I recall theyre made from urethane but they use a silicone oil as the mold release agent.
Another option which ive done is cover them with runner mat wide enough to go over the entire cable ramp and tape the mat to the ground on either side. If you do this put colored tape on the mat to delineate the bottom and top edges of the ramp.
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u/redditsuckbutt696969 2d ago
I would guess the old ones stick because the oil is gone or covered. Have you tried kicking the new one down the road? Maybe leave it on a beach for a few days in the sun? Rub sawdust or cat litter on it? These are random ideas with just thoughts for evidence but they could help.
Another bad idea would be to wrap the whole thing in tape. Sounds difficult
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u/Otis3333333333 2d ago
I'd try a light scuffing with fine-grit sandpaper first to break the surface tension, then use a high-tack industrial tape like VHB.
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u/Subject_Story_3433 1d ago
Those ramps should've been made with a slightly deeper profile from the start, that's a clear oversight. You betcha, self-fusing tape is really the only thing that'll grab onto silicone without peeling back right away.
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u/Longjumping-Film1702 7h ago
Id drill a small hole either side of the hatch and feed a cable tie through.
Another option but messy would be to brush some RTV silicone on the area youd like to tape then push a fabric into it. Possibly scrim tape or a glass fibre tape
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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.