We’re fairly new to the Form 2 and we here love it so far. However, we did have one question. We bought the Form, Wash, and Cure at once. The documentation we have found states that you need to take the print out of Wash for approximately 30 minutes to allow the alcohol to evaporate before entering the Cure. However, while the Flash Point of 91% IPA is only 12°C, the auto-ignition point is 399°C. The Cure itself is 60°C. So what’s the thinking/worry of going from one to the other? Does the IPA need to evaporate due to the fear of ignition, or are there parts within the Cure itself that would be susceptible to the corrosive properties of IPA? Just trying to understand, as we have a lot of prints to do, and if we could avoid a 30 minute delay between those steps, it would help.
We use the Wicked Engineering cure box and they recommend that you wait until the IPA has evaporated. My guess, and it’s only my guess, is that it’s more based on lawyers and liability than it is science…
I have the exact same feeling and have expressed it several times here, but of course Formlabs can neither confirm or deny this as there is a liability issue in both situations.
To offer a reason for the safety recommendation : the Cure is an electrically powered device, and sparks aren’t out of the question. In theory, if the device is filled with highly concentrated IPA vapor (very unlikely, if at all possible), an electrical spark may ignite the IPA.
The question of causing cracks is not realistic IMHO. I believe that if you place the part in the Cure when it is still wet, upon starting the Cure the slowly (very slowly) increasing temperature and low airflow will make the part dry slowly enough for the IPA to not be a problem.
That being said : for big, thin parts susceptible to bending, I would still wait for them to dry before putting them in the Cure, just to be sure.
Try it with High temp resin. It will make a huge difference. I can guarantee you that they will crack. For the other resins, you might simply not see it. About a year ago I posted tests and results here on the forum.
The concern isn’t so much that the IPA will auto-ignite from temperature, but potentially from a spark generated by the electronics. The problem is that all of the IPA has evaporated and created a really nice air-fuel bomb - just add spark.
As for real risk, I think it also depends on the concentration of IPA that you are using. If you are using 99%, then it is a real risk. If you are using 70% it’s hard to imagine a real problem.
I have put prints wet with 99% IPA in the cure box without incident but…just 'cause it hasn’t happened doesn’t mean it can’t. Am I worried about it ? No. Will I do it again ? Yes.
I have putting wet dental models in formcure to save time in the clinic. I would also be interested in an answer from someone of the tech guys in Formlabs wether we should be doing that or not.
I have one more question though if I blow dry my models to evaporate the IPA before curing will that damage the surface finish of the model in anyway?
I used to never let my parts dry until I noticed an inconsistent discoloration on my parts printed in gray and clear. By letting the parts dry for 1/2 hour to an hour before curing them, I haven’t seen the discoloration at all.
Interesting, we’re printing in Black at the moment and will see what it does. The first print looked fine going from Wash to Cure immediately, but it should take more than a single data point to come to a conclusion.
I also put parts with IPA straight into cure (usually 70% but I will admit I have done it with 99%). Never had an issue and I don’t think it’s likely. I will say that I don’t leave it unobserved and we have fire extinguishers close by. Likely the worst that would happen is that I would buy a new Curebox. Once there is someone here in the shop other than me I will stop this though.
I would also note that if you are concerned about surface finish the best outcomes I have had I have gotten with making sure I get a thorough cleaning using fresh IPA and a sonicare followed by applying Curegel (from Wicked Engineering) for the post cure. Supposedly oxygen can inhibit the cure - Curegel blocks the oxygen but is UV transmissive. I water cured for a while but while it was an improvement it was not ideal.
Official answer I got at a support ticket I made on the subject is do not put wet models at FormCure, if you are in a hurry blow dry the model and then postcure the surface of the model is not damaged or become matte by blow drying.
Thank you DG for putting in the extra effort for a support ticket. I’ve done a few prints now without pausing between Wash/Cure and have noticed some changes in the color (black resin) when we do/don’t let it air dry. Nothing is damaged it appears, but the coloring seems a bit off in areas that had more IPA on them than others.