Rinsing bath - how to disposal ? when to change?

First, sorry for my bad english, i’m french. I hope i could be clear.

As i read it on Resin Care’s Page ( http://support.formlabs.com/entries/23388626-Resin-Care)

> Liquid resin (whether pure or dissolved in alcohol) must be disposed of with care. You have several options:

Cure the resin in sunlight or under a UV lamp. Then dispose as normal waste.

I’m a bit suspicious with the fact to cure my rinsing bath (lot alcohol and some resin) with sunlight, when i read the MSDS from alcohol witch mention a flash point at 13°.

What do you do with the rinsing bath ?

Also, i wonder myself if there’s some tips to know that you should change the rising bath ?
Is it enough to add alcohol to keep the level ? (then no rising bath to disposale ?)

thank for your help :slight_smile:

1 Like

bump ?

This is a good question that deserves an official answer.

vendors generally supply MSDS and then specify to handle products in accordance with local safety and disposal regulations - naturally calling out any general hazards like shock risk, corrosion, etc. it’s challenging to specify best practices given how diverse the rules and regs are around the world, and even with specific institutional guidelines in many cases.

Hey guys,

Jason is correct. You can check out our MSDS here:  http://formlabs.com/products/material

Please investigate local regulations in your area for hazardous waste disposal. Laws vary depending on where you are.

Google is a good tool for researching this information.

OK, so we should dispose of it the same way we dispose of all of our other Methacrylated monomers. I’ll look into this “Google”.

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Thank you for your answers, but I have not been clear.
I read the MSDS for the resin and alcohol, I contacted the French authorities (as I’m French) for the recommendations disposal of these wastes.
This is actually the most logical for a person who is concerned about the ecological solution.

But I just wonder  about manual (http://support.formlabs.com/entries/23388626-Resin-Care) gives surprising recommendations as I mentioned above because I read about 2 MSDS.
This recommendation (about UV) has not been written “at random” and I want to understand what motivated this writing.

Finally, I would like to know if there was a trick to know when to change the rinsing bath? or just add alcohol to complete evaporation? (in which case no waste?)
Or if there are many waste bath rinse to treat ? can anyone give an indication of the amount to be treated after X impressions or the use of X liters of resin?
Because as i said i contacted my authorities and i need to know how much wastes to treat to know the cost.


With the explicit understanding that local regulations regarding disposal may vary for the reader, how does Formlabs dispose of alcohol bath containing cured resin?

TY @Jason Hsu it’s more clear than me ^^

and also how many “alcohol bath containing cured resin” do/will we have to dispose ?

Hey guys,

Apologies on the late reply.

We are working on drafting up an article to help point you in the right direction for waste disposal. When it is completed, I will link to it here.

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@Jory, great :slight_smile:

On the same subject :  http://support.formlabs.com/entries/24130983-How-often-do-you-need-to-change-out-the-alcohol-in-the-rinse-bath-

Nearly subject :  http://support.formlabs.com/entries/23704573-Clean-er-Alcohol-for-Clean-er-Prints

“This recommendation (about UV) has not been written “at random” and I want to understand what motivated this writing.”

The reason for UV curing is that once the resin polymerizes into it’s solid form it is relatively inert, and can typically be disposed of in normal garbage, as any other [non recyclable]  plastic. [check your local laws to be sure] In the liquid resin form, you likely have to treat it as hazardous waste, like paint, and take it to your local chemical disposal facility, as it could leach into the ground water system if disposed of improperly.

As for the used alcohol, that should be disposed of as hazardous waste. Another option might be to evaporate off the alcohol and burn that [as it will be clean] and then dispose of the remaining residue by exposing it to UV to cure it, and then throwing it out, or, as above, taking it to your local hazardous waste drop-off.  At the very least, evaporating off and burning the alcohol minimizes the volume of waste you need to dispose of.

@Mark Loit

In France, legislation has adopted the principle that the polluter pay. This principle drives actually want to reduce industrial waste.
This is indeed why I would like detailed informations on the method by evaporation of the alcohol, or best a direct testimony of someone who really practices it.
I would like to be assured that this method is not dangerous in its implementation.

I was in the chemical industry for 27 years and handled IPA 20,000 litres at a time which was fun!

To be totally honest with everyone who is interested in this subject you are each going to have to discuss the subject with your local authorities to find out how the contaminated solvent is to be disposed of in your area.  I think you will find that most Western countries expect the polluter to pay.

Countries have very different laws for handling chemical waste which have to be respected.  You will need an MSDS for the IPA which by law the supplier should make available to you.  You have the MSDS for the resin from the Formlabs web site so you have all the information the authorities will need to advise you.  If you are a business you may have different guidelines compared to a person in a private residence.

It’s also worth mentioning here that storing over a certain quantity of “Flammable” material  in your property can invalidate your insurance if you have a fire.  So be sure to check with your home insurer what their rules are.  I use IPA in another process and have extended my insurance to store up to 25Ltr  IPA in a flammable cabinet among other solvents in an outbuilding.  I know some are going to say “but I park my car in the garage which is joined to the house and that’s full of petrol”  well yes you do and your insurance will already take that “risk” into account.  That’s why they ask you where the car is parked.

Practices like evaporating the IPA off or burning it may be against local regulations after contamination.  Businesses may have VOC limits limiting what they can evaporate anyway.  These practices have inherent risks so take precautions.  If you are using IPA only for the printer the amount of waste is not going to be too high so the costs are going to be very low I am sure.

@Nigel Wagstaff, TY very good advice for insurance !

How about not even trying to dispose of it, instead recycle the IPA to pure IPA and then just solidify the remaining resin in the sun?

Keeping it simple along the line or similar to something like this?   http://www.brewhaus.com/instruction-pages/Amazingstill-Instructions.pdf

Marc, the still is perfectly feasible in a laboratory or industrial environment.  The thought of heating alcohol above it’s flash point in an enclosed environment like the home will one day go horribly wrong.  I am not Mr.  Health and Safety here just trying to point out the risks.

The heaters do look like special units, and designed for immersing in weak Ethanol solutions, but I am not sure they are designed for immersion in almost pure alcohol as we will have.  If the electrical insulation fails inside the heater at any time and there is a spark I can assure you it will blow every window in your house out an your ear drums in!

Iso Propyl Alcohol  is not Ethanol.  It’s an industrial alcohol which is more toxic compared to Ethanol commanding some respect in use. It burns very hot with an almost invisible flame so you should practice strict no smoking or ignition sources in the vicinity and you should avoid skin contact as it will adsorb through the skin. Like most chemicals, used correctly it is safe.  Store it like your household cleaning chemicals locked away from children and ventilate when open.


@Marc Collinson, As Nigel Wagstaff said, it seems to be a bit dangerous with a flash point at 13°. Also, i’m in France where distillation as a hobby is illegal.