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US-IMF Material Update

Hi everybody,

This is a small infomercial concerning some of the product elements that will be in the KS:

A few of the parts for some of the models, in 15mm and 28mm, are going to be produced in 3D print resin, not cast resin.

We were going to put that info into the upcoming monthly update however, something occurred elsewhere that we felt we needed to address directly and “nip in the bud” before any issues were created.

First, some technical info:

The liquid (uncured) resin used in the SLA 3D printer is slightly toxic – it can cause skin irritation and if swallowed or brought into eye contact can leave chemical burns or make you sick.
You must not handle it without gloves and don’t get it near your mouth or eyes. (The MSDS for the resin is here: https://formlabs.com/media/upload/Grey_Resin_SDS_EU.pdf )

However, the CURED resin is safe – you can handle it without issues and it’s perfectly safe to use like any other resin and with the same safety constraints as a normal polyurethane resin. It takes primer and paints perfectly well and has a similar shore rating as many commercial polyurethane resins used in the modelling industry – in other words, it’s just another resin.

Note: this is on the basis of the resin having been post-print cured for the relevant period of time in the “Form Cure”: until this is done the material is not considered fully cured and therefore safe (after post-cure it is considered non-hazardous and safe, and therefore no longer requires an MSDS)

So what?

We were contacted by the backer of another KS who is also a backer of US-IMF. They had questions about the use of 3D printed resin and whether or not we might be providing any of our parts using the same resins because….: (cont)

The “issue” that we need to address is that a recent Kickstarter has been providing its customers with 3D printed parts – those parts produced in the resin that we use and on the 3D printers we use i.e. the same stuff we intend to provide to you.

However, the parts that this KS producer has supplied have not been cleaned properly – they have not been washed in isopropyl alcohol to the correct degree (and using the appropriate equipment) and they have left uncured liquid resin on the exterior of their parts (as is usual from the print process before washing).

However, they have then sent out these sub-optimally washed parts to their backers and those backers have then questioned what the sticky gunk is on the parts they have received (at which point it was bought to our attention by the above backer who knew we used the same resin and printers)

Unfortunately at this point the people running that KS decided that rather than admitting they simply haven’t washed the parts properly, they’ve come up with a fabrication to explain away the gunk on the parts – they claimed that the parts have “sweated” uncured resin from inside the part, through the cured resin and on to the outside… resulting in the “sticky gunk” on the part …. and that that has occurred because of the hot weather (in the UK) which has created an internal pressure that forces out uncured resin from the internal cavities in the printed parts through the resin parts exterior.

At this stage we would normally just roll our eyes at the excuse and say nothing in public, however, in this case, we felt that, as we were going to be sending out some of the exact same resin from the same 3D printers, we needed to unequivocally clear up any misconceptions about the process and resin, thus:

The information they have provided is rubbish – cured Formlabs 3D printed resin is impermeable (It cannot sweat anything through it: it is literally impossible.)

As such the meme that ‘Formlabs 3D printed resin can sweat liquid resin when warm’ is completely, absolutely, unequivocally false.

Back to us:

We won’t be sending out any production parts with hollows in them – it weakens the parts, saves no resin, can produce printing issues and is generally bad-practice in any case.
On top of this, ‘theoretical’ damage to a hollow part could result in internal un-cured resin leaking out through cracks/damage – however, as we only produce solid parts this was and is never going to be an issue.

We also “Form Wash” and “Form Cure” every component (for ourselves or for a customer) – and so in no circumstances should you ever find any uncured resin on the outside, or the inside, of any printed part. (indeed we would not be able to supply any such parts without sending with it an MSDS and appropriate warnings).

Therefore, if you see this “sweaty 3D resin meme” anywhere PLEASE ignore it;  it has no foundation in reality and is merely an example of a KS producer inventing a narrative to cover over a knowledge deficiency.

“Sticky gunk” on the outside of these 3D printed parts is down to not washing parts properly and/or not post-curing parts and that is that.

It is not something that any of you will have any problems with (on parts supplied by us), and there is nothing to worry about using such parts, the resin and so on and so forth.

NB:

We’ve made this statement to refute this invention about “sweaty 3D printed resin” – it has already influenced/concerned one of our own backers and we simply do not want this misinformation to spread any further, or to raise any concerns over materials we may supply to you.