Ember Standard Clear - Mechanical Properties


Does anyone have some data regarding the tensile properties/mechanical characteristics of the std-clear resin? I couldnt find it on the website.


We did some testing a while back, but the results varied so much depending on orientation and post-cure. If it helps, here are charts of the results:

Physical and chemical Propertires of PR48

Could you please say, is modulus mentioned in one of the charts a Young’s modulus? If yes, why it is so low? It is around 600 psi, which is 0.00413685 GPa. Wikipedia says, that even rubbers have Young’s modulus up to 0.1 GPa.


Good catch! It was mislabeled – it should be MPa, not PSI. I’ve re-uploaded the image with the correct units. And yes it is Young’s Modulus.


This is a really good info! I am just wondering, what is the exactly the orientation of the object on the platform, when you print 0 deg and 90 deg? What is the difference? Is it possible get any images or print screens of 0 and 90 positions?
Moreover, where can I get more info about postcuring? Does “Poscture” mean you kept the object under 405 nm light irradiation? For how long?

Thanks in advance!


Hi Edvinas! We don’t have any images of the tests because they were done by third parties, sorry about that. I believe the objects were dogbone-type test specimens printed vertically (the long axis of the part parallel to the Z-axis), so 90° orientation would look like this:

And 0° would be with the samples rotated on the Z-axis.

For post-curing, my guess is that they were cured in air with 405nm UV light for 5-10 minutes.

Hope this helps! Unfortunately the results are pretty inconsistent, which is why we didn’t publish those graphs until someone asked for them.


How about printing a thin layer (single layer thickness) horizontally and testing that one in order to to avoid the effect of print orientation due to different lamination?


I think there are two aspects of Mechanical Properties in 3D printing:

Actual material properties: If you were to pour the material into a mold and fully cure it at a given thickness this would give you the exact material properties (theoretically).
Final Print properties: This takes into account weld lines due to print orientation, light variations, and all the other variables associated.

Ideally, they would both be the same, but they never are. To perform a fully scientific evaluation of Mechanical Properties, both need to be examined. For application purposes, only the Final Print properties need to be examined.


This is something I have noticed where the bulk Young’s modulus is quite different than the Young’s modulus of a thin membrane (3-5 layers thick). My thinking was that the effect of layering on the Young’s modulus at this small scale is substantial, since using the bulk in models for the system are very inconsistent with the experimental results I am getting.


Hello everyone, have anyone tried to determine the main properties of PR48 resin such as density, viscosity and etc (when the temp is 20-25 celsius degrees)? thanks.


The density should be in the range of 1.13-1.14. The viscosity is highly dependent on the temperature. In the range of 20 to 25 DEG C the viscosity could easily vary between 250 to 400 mPa*s.


We are interested in experimenting with PR48, and would like to understand more about it from a chemical perspective. Our contact said to include @CPS in this post.

A general model of the interaction of the photo initiator with the base and how sensitive each element is in relation to others; whether they react in a linear way, and how varying PR48s ratio may help promote different physical characteristics.

Our more general aim is to put the process under AI control, rather than perfect a craft use, such as jewellery.

If there are any other chemists out there, please get in touch.

Mercury Algorithmics
San Francisco


Hi Mark

This sounds like a fascinating but very challenging project. The interactions that take place during a photopolymerization are very complex. The reaction starts when the photoinitiator reacts with a UV photon to create a free radical species. There are multiple pathways that a photoinitiator can form a free radical, depending on the chemical structure of the photoinitiator. In the case of PR-48, the photoinitiator used undergoes photocleavage which is one of the simpler mechanisms. Once the photoinitiator cleaves, it forms the initiating species which can react in several ways. Many of these interactions are non-linear. Which is why formulating new UV Curable 3D printing resins is a challenge.

There are some general trends. For example, the Ebecryl 8210 is used as the base resin as its high molecular weight leads to low shrinkage and it has good crosslinking capability. The SR 494 is used both to lower viscosity and provide good crosslinking. The remaining major component, Genomer 1122 is used to reduce the overall viscosity and also help with adhesion to the build plate. All three of these components interact with the free radical to form the resulting cured polymer.

If you would like a more in depth discussion please contact Dr. Mike Idacavage on the Contact Us page at www.cpspolymers.com.


Thanls for the introduction, whcih is much appreciated.

Regards, Mark


I’m consolidating info about PR48 into this thread, which is why the last few posts have older dates.

Someone else just asked about the Tg (glass transition temperature). @bad-zima says it’s ~40 °C at room temperature, but it could change if the room temperature changes.