Epoxy Lens

I 📌wondered what the result would be if you used cling film with a pressure difference as a “mold” for a lens? I did not find many people trying it. Here is my humble attempt.

Another experiment, i may want to try later, is spinning the epoxy while it cures. That idea adds the problem of the bottom surface. Perhaps the bottom can be made level by a second pass where it is done upside down. I found one instance of this being done, although i could easily have failed to find other cases.

Noticed from reading online the dispersion of epoxy is not much, that aspect is possible. Given the precision necessary i do not expect much of a lens from either experiment, also my attempt may be quite far from perfectly executed. Still i feel that someone should try.

About the cling wrap, it is probably made from linear low-density polyethylene (LLDPE) if you believe wikipedia on this. I am not at all sure about the formulation of the clear Epoxy.. The store i got it from says little about it. Perhaps that is strange.

I think the shape the lens will take is possibly not quite a shape you’d need for a binocular or whatever. But it’ll be … something.

First cling film attempt (2022-04-23)

I had cut the bottom of a plastic bottle, also cut a hole from a plastic bowl, and glued them together.

The idea is that i close the bottle cap put water in, put the cling film over the bowl. And then drain water from the bottom, which lowers the pressure, and causes the cling film to bend.

Also make a stand for this, also from garbage.

I was thinking of this experiment based on how you can make a nice flat surface using cling film and a glass bowl. You “drum” on it.. In practice with this plastic bowl it did not stick so well, so i feel like i need to retry it differently. Perhaps try create the pressure difference via a temperature difference.

I also put the cling film on and then made the epoxy, given the former did not stick well, the pressure difference across the film may have been lost. Despite that, it largely kept it’s shape.

The set epoxy and the cling film separated easily. The result was a lens, but a pretty bad one.

Using a ruler, it does seem it warped a little and the flat side is now concave.

Second attempt (~2022-07)

Went dismally, didn’t hold pressure and did some half-assed stuff that basically ended up with puddles. Basically cling wrap does not cling wel to the thing i have, and it put stress on it ripping it off..

Occurred to me that probably for now the lenses are far enough off that a photograph can map how they’re off.

Note: also tried “denim fibre” using bits cut from some old pants, but didn’t come out so great really dark and it was too much resin. Though also think perhaps it comes out better with better planning.

Conclusion

As noted, i want to use a material for the bowl that the cling film actually sticks to. When it does it’s also possible to tweak it a little as needed. However, for glass bowls i have it’s not obvious how to get a good pressure difference across it also.

The other experiment idea, spinning the epoxy, think i want to try that, that would require a bowl to rotate consistently without oscillating otherwise for hours.

I am content even if the lenses are not great..