A bit of resin alchemy


Your IPA vs YM testing is interesting. Do you have any details about this or is this mostly your general observation over time?

RE: snapfits: yeah, clear works, but cannot hold up to repeated snapping/unsnapping. My snapfits are not a typical cantilever type, but rather an all-around snapfit where there is a substantial amount of hoop stress aiding the tigtness of the fit.

I agree that tough on it’s own is not very good at precision. My mix has just enough elasticity to not fracture, while still holding tolerances very well.

RE: gasket: Yes, I also do make hard and silicone molds for parts that those methods are best suited for.

Can you post pics, details of your vulcanizer and process? Sounds great!


There are instructions on YM here

I had recieved a tough part sample and it was brittle in a week, compared to the clear parts I have that seem to stabilize. You should be able to deflect them no more than 30%.

Here is a sample of a recent casting job I did with some really small text. Text is a little rounded from the tumbler.


Most interesting. Has anyone used Yellow Magic 7 with the castable resin?


David Miller has been using it on the castable resin.
Not sue if it is necessary with the castable or not unless you have shrinkage and part distortion dorm IPA.

I use YM because many of my parts are flat and thin and the IPA was making them into potato chips. It is nice to get away from the toxic sludge IPA creates and be able to recover the cleaning solution.

The Ultrasonuc Cleaner I picked up from Harbor Freight. It is a cheap u it and I recommend sealing around the inside lip of the tank where it meets the rest of the unit because it will allow solution to get inside the unit. Not the greatest design but an easy fix and it is a good working machine for cheap money.


so ken, can you link that cleaner please ? i have some YM but without a cleaner i think its terrible… it doesnt seem to get any resin off… so hopefully the cleaner is worth it.
thank you


I am quite happy with this 10 liter unit myself. They also make a smaller 2 liter version.


Is that your workbench’s surface beneath? Nice!


I use a small ultrasonic cleaner on castable after I’ve been working the resin before casting. I let it dry off then it’s straight on a tree


This is the one I have:

You could probably use shipping tape or silicone caulking around the inner lip where the tub meets the rest of the unit to make it less messy when draining.


Ya my work bench is pretty well worn, used to build fly rods on it for many year, Has a few scorch marks from casting.


Have you received the dry heat uv sterilizer? And is it worth the investment?


I bought a dry heat UV sterilizer and wrote it up on this thread, if it is of use to you.

BUilding the Ideal Cure Box


I now use a mixture 75% Black and 25% Tough (mixture by weight). This was printed on the Form2 in a Black cartridge ie with Black settings. We call the mixture Blough. And it works quite well for us. We make precision engineering parts, that is parts for mechatronic, everything from rice grain size to golf ball size. Almost everything is printed in 25µm setting. Parts with Blough also have snap-in assembly constructs.
Blough prints very well at 25µm, has excellent detail, and is impact resistant, and is stiff enough for mechatronic prototypes. I don’t have too many problems with removing it from the platform; but I do use cans of cold air (<-20°C) to avoid problems - alot of the parts we make have details smaller than supports.
Blough is not smelly like Tough and I don’t have an issue with post-curing the surface (as tough can have)

I will also try clear 75% + tough 25% and white 75% +tough 25%, but only because I have liters of white and clear which I do not like:
White (Ver2) is difficult to remove from the platform, brittle and you can print at 25µm.
Clear (Ver2 and Ver3) is too brittle. It gets more brittle and yellowish in the sun.

Comments about the other Materials:
Tough is too flexible for my liking, stinks and the dimensional stability isn’t very good - parts come slightly warped, probably due to the low heat distortion and low elastic modulus.
Black is the better standard material, but is still too brittle.
The Durable that is coming out next year has a very very low flex modulus (I only have the current published values, obviously not tried it) and is extremely flexible, so I wonder what the difference between Flexible and Durable will be for practical purposes…


Thx mdmr for the info. I’m really looking forward to use blough as well for the same reason: standard is too brittle. I suppose blough doesn’t look much different then black in terms of color??


@3DYeti I’ll post some close-up pictures next week. The prints are almost black. I think i had some dark grey lines on the first print, but have since then sloshed the mixture around in the cartridge more before printing. I am not too bothered about colour, but for those who are I will send a picture.


Which tough are you using for Blough? There are now three versions.


I use the latest resin versions. Apparently there was a noticeable difference between the last and current Tough, I only started with the current tough version.

I don’t have any models with Black pure left, so cannot show a comparison.
Below is a comparison of a black injected molded part and Form2 3D-printed 75%Black-25%Tough models, printed in the 25µm Black Setting, ie from a Black cartridge,. The metal paper-clip is for scale and contrast, made of 0,8mm wire.

I would describe the 75%Black-25%Tough models as being anthracite in color. Most would just say black…


Hi Mrdrm,

I have a few questions:

Can blough be polished with ease?

Is there a method for curing internal volumes?

Does blough require agitation over time?



I haven’t tried to polish. I can polish and will get back to you on how I manage.

What are internal Volumes? Do you mean trapped resin in a body? If that is what you mean, then there is probably no way of curing them. The penetration depth of light will be very small (perhaps 10µm) and so there won’t be any way to cure hidden volumes. I normally construct a “flow hole”, it should be more than Ø1mm, so that the fluid can come out. You will also need a second hole to let air get into the volume, otherwise the fluid will not flow out. You can also inject air into a hidden volumen or flush the resin out with a IPA mixture.

When we mix Tough with Black we fill the cartridge on a scale and calculate the added components by mass. We use a scale with at least 1 gramm accuracy. An empty cartridge weighs approx. 300g; full approx. 1420g. The cartridge has a narrow waist (see picture) and so when you slosh the mixture around it actually mixes quite well. I initially mix for a good 5min, but we have decided to mix for longer just to be case. It probably is an overkill mix time.

Another tip: we only fill the cartridge half full, this helps mixing and also IF there is the dreaded valve failure, then only half the contents of the cartridge will leak out.


Thanks for the tips. Yes, hidden volume is a better way to describe what I’m referring to. I am planning on printing parts with internal air passageways. I am trying to decide if I need a translucent material or if opaque will perform well. The parts I get from an SLA shop are in a clear acrylic and it is cured evenly through the entire part. The part has a maximum thickness of 6mm.

Very curious about polishing. I finish all my SLA parts with an abrasive process with final polish. I’m hoping to be able to do this with a Form 2, but I’m looking towards Blough for improved ductility and impact resistance as these parts are used in luxury consumer products. The resin my SLA shop uses has performance characteristics between that of clear and tough.

I’m choosing SLA because of rapid design changes and exotic internal geometries that simply cannot be produced without very expensive injection tooling and snap fits.