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I’m a big 2-part resin crafter, so my question pertains specifically to the interactions between ferrofluid and resin.

I recently acquired a large glass tube with open ends and I’m trying to figure out how I can seal the ends of the tube to use for a ferrofluid suspension. I’ve read in several places that glass containers are best for the storage of ferrofluid, but every bottle I have seen used for this has a plastic cap/threading. My question is, can I get a flat piece of glass for each end of the tube and use two part resin to attach the pieces of glass together and possibly coat the outside of the tube with resin before adding any suspensions or would it seep through the resin? If I can’t use the tube, how do I get a good seal on a glass bottle that has a petroleum product-based cap?

TIA!

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Ferrofluids can have differing compositions. There is always a ferromagnetic component, such as iron oxides, metallic iron or nickel powder, but the viscous liquid in which the particles are suspended can differ. For example, a vegetable-oil base could be stored in any container that one might store the vegetable oil itself, such as clear polyethylene terephthalate (PETE or PET), widely used for food sales and storage. A surfactant such as oleic acid can be added to help keep particles suspended, but that should not attack most plastics.

If kerosene is used to suspend the particles, one might use a stronger container, because of kerosene's greater flammability than oil.

That said, plastic scratches far more easily than glass. After some time, the ferrofluid might abrade the container walls, or leave deposits on any rough spots, clouding the container. For long-term use, I'd use glass, with a plastic or metal cap.

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  • $\begingroup$ (+1) Also, could a rubber cap be used? Something similar to a lab stopper? $\endgroup$
    – Ronith
    Commented Jun 3 at 4:01
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    $\begingroup$ There are many types of rubber: nitrile, neoprene, silicone, usw. See the list at Mykin, for example: mykin.com/rubber-chemical-resistance-chart . Decide what fluid you'll use (kerosene, mineral oil, etc.), then pick the appropriate stopper. $\endgroup$ Commented Jun 3 at 4:43

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