IPA grades

Very new to SLA printing. I was dismayed to find that, during this pandemic, operating SLA printers requires a not so insubstantial volume of IPA or other chemicals for cleaning residual resin off prints. Needless to say it’s very hard to come by at the moment.

I’ve found some “technical grade” IPA. Would this be sufficient for cleaning prints before curing? Or is some other higher quality grade needed?

Usually IPA is labeled with the % alcohol it contains (e.g. 99%, 91%, 90%, 70%, etc). Formlabs recommends 90% or higher. They used to recommend even higher, but backed off as apparently lower concentration is safer to handle as a household chemical. I’ve also been told 99% eventually evaporates down to 90% dilution anyway when not sealed.

Personally I find it most cost effective to buy 99%, and mix it with distilled water to dilute down to 90%. I keep some 99% in a bottle for spot work.

“Medical” grade alcohol that isn’t otherwise labeled might be only 70%. I’m not sure about “technical”.

Locally, I’ve heard supply distributors for the film industry still have some gallons of IPA in stock (propmakers, etc) as the film industry is largely shut down.

EDIT: TPM is an alternative that may be easier to source right now.

Good luck!

As it was a challenge recently to buy IPA, I tried methylated spirits. It’s 85% and costs 1.35 per liter.

It works great! Just smells a bit and I’m not sure if it last the same time as IPA.

DPM also works really well.

So from what I’ve gathered “technical grade” 99% should be fine for this. It’s usually cheaper than higher grades meant for labs, medicinal purposes, or cleaning food prep areas.

@fantasy2 that sounds interesting. I’ll have to see if I can find some.