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Could duct tape be used rather than fiberglass cloth when making something that would normally be of fiberglass? Answered

I am just trying to find an easier way to mold fiberglass at a very large scale. I am thinking that duct tape would be just as good fiberglass cloth but i have never had any experience with molding or with fiberglass.

If it does not seem very realistic, could someone point me to something that is a bit more reasonable?



Best Answer 7 years ago

An interesting experiment was recently conducted on the BBC programme, Bang Goes the Theory by Jem Stansfield. He created a small boat from a material called "pykrete" which is ice with a submerged material. In this case, he used hemp fibres soaked in water and frozen into a big chunk.

Glass Reinforced Plastic is a similar idea to this. The resin is fairly hard but brittle, the stronger glass fibres are needed to make it tough and resist the cracks.

I would therefore assume you could substitute the fibreglass for another material that could be soaked in the resin and provide similar effects. This is how carbon fibre was created.

As has been said, duct tape will not soak the resin and therefore won't bond effectively. You could use strips of fabric like nylon or polyester to good effect. Fibreglass and carbon fibre are good because they are stiff, and similar stiff materials aren't as readily available. I have heard of fine steel wool being pulled into strands and mixed into resin.

To be honest, the resin is just as nasty as the fibreglass in my opinion. It is the resin that makes working with fibreglass difficult because it sets so quickly. As long as you wear gloves, goggles and a mask in a ventilated environment, fibreglass will cause you no problems. Stand under a good hot shower afterwards too.

Use blue shop towel, works great if you don't need a bomb proof final product.

We make fiberglass moulds for casting concrete and find it much better to use "membraine" used to seal wit a paint application

Duct tape is neither as strong as glass fiber, nor does it let the polymer soak into it and thus be reinforced by it. Not equivalent in any manner.

What problem are you trying to solve? Why isn't fiberglass "reasonable"?

I don't mean that fiberglass is not reasonable. I just don't know anything about fiberglass and it doesn't seem like something that could be molded into huge shapes at home. Using duct tape at first sounded like a good idea because it is available and can be used to cover large surfaces. I need something very lightweight and strong that i can mold into fairly large shapes. Do you think it would be sensible to mold something about 8 feet long using fiberglass?

Yeah, you can do that at home. Build a mold out of foam insulation or a frame out of wood, and layer the fiberglass onto it. It's smelly and messy, but the materials are pretty easy to acquire and there's plenty of info on the internet.

Fiberglass canoes are often 8 feet or more.

Whether fiberglass is the right material or not depends on what you're trying to do -- how durable does it have to be, how strong does it have to be, how finished an appearance does it need to have, and so on. Without a lot more specifics, I have absolutely no opinion on whether fiberglass, cardboard with duct tape, wood, carved foam, or anything else would be great, good, bad, or awful.

Is duct tape a replacement for fibreglass cloth? Not if you plan to use resin to harden it. As a total replacement as a 'apply to a frame to make a sheet of something water impermeable and somewhat strong' -- yes.

If you're thinking the mythbusters duct tape canoe then very similarly, they did a great job with it, stiff frame, layer stretched over adhesive OUT, then another layer to the bias glue IN, to make a nearly-permanent glue-to-glue contact.

Also, remember, duct tape has TERRIBLE UV/sun performance -- it will dry and crack and make you sad as an outdoor material.

Take a tip from the pros. There isn't a seriously different way to deal with GRP - In the pro world they often spray the resin and chopped mat through special spray systems but other than that it is down to very smelly hand work - that's why high end GRP is so expensive and why for mass production products are moulded where possible.