Hazing on resin tray ... what to do next?

Hi all, I understand that this issue has already been asked a couple of times. I’ve also logged a ticket with the technical team but would like to see if the community might have anything new to add or maybe found a way to reduce the chance of hazing, etc. Basically, I have found hazing spots on the silicon surface of the resin tank which I’ve uploaded two videos on YouTube. The first one was taken a week ago - https://www.youtube.com/watch?v=kSKjKavr92Y The second video that I took just yesterday shows the same hazing but this time the silicon layer has a small indentation. I believe that it might be casing some prints to fail. I have had two print failures already. The link to the second video can be found here: https://www.youtube.com/watch?v=1Buiyh_MrdU

Also attached are the failed prints. You will notice that the prints concentrate / occur in the same area. The second print has a larger “hole” and the surface itself has not been printed. It’s a disappointment as we are working on a research project and have had severe delays first due to the detached screw thread (now resolved) and this time the hazing and tears in the silicon layer.

Any help / advice / suggestions are welcomed.

Thanks all.


Unfortunately, hazing can not be avoided but it can be delayed.  Now if you printed a very low number of parts and this happened FL may work with you in getting a replacement vat.  If you re-orient your parts and move them around the build platform you should still be able to use the vat and avoid more delays.  This will also help avoid the hazing from forming.  It will be more uniform over the entire vat surface.  Massaging the PDMS layer will help get some of the hazing to dissipate but it is not a perfect fix.  I believe there is a great write-up somewhere on this site.

I see only 2 ways to resolve the issue with this vat:

1:  Purchase a new vat from Formlabs.

2:  Buy a PDMS “kit” and replace the silicone layer.

If the print took the chunk out of the silicone layer, I would reduce the surface area of the pealing layers.  i.e. reorient the part.  It looks like the parts are shelled but printing them oriented differently should help.

If you accidentally took the chunk out of the silicone layer…. Well I have done it.  It sucks.  This one of the reasons why I have 6 vats and 3 of them need to have the PDMS layer changed.  I have just been lazy and have not changed it yet.

Hi David,

I only received the Form1 last month and have printed less than 2 dozen parts of which nearly 30% had poor prints / failed prints / incomplete prints. Some were due to the CAD file, others due to issues such as the peeling motor being dislodged; or another case where I didnt remove the plastic wrapper from the resin tank (in the first day of using), etc. Those issues have been largely resolved but this one which is the hazing of the resin tank will be more pronounced in days to come. Ideally I wouldn’t like to consider purchasing a new tank as it’s not even half a year of using and the tanks cost money, especially so with shipping. Yes, I have tried moving the build parts. Previously I built them dead centre, but those two failed prints were built off-centre and more towards the front of the tank. Sadly the failed prints still show. It’s a good idea to re-orientate the parts but it is not a long term issue as printing this way not only means taking a much longer time and also more material for the supports. I have printed some parts tilted. they have turned out fine, but I suspect that this is not the best way to go forward. The key really is to find a more robust material rather than using PDMS as the base layer for Resin tanks. Some have suggested glass tanks (Pyrex?) but there’s an argument about safety an also about the laser dispersion, optical clarity and costs involved in manufacturing. I’ve come across an article that talks about changing the silicon layer on your own, but why should customers go through the whole hassle of making this? It is in the long term not sustainable. Hopefully someone from the Formlabs technical support will chime in and also reply to my ticket. Hopefully I won’t need to purchase a new tank as it’s been less than half a year, maybe 3 months?


I have found that vats last in # of prints not time.  I do not see a vat lasting months if it is being used everyday all day.  Vats are considered consumables.  This is why FL is selling them.

Actually printing the parts up on an angle are the best way to print.  Yes, this way uses more resin but the prints are better, there is less warping, the surface area for each peel is less, etc.  All these will also help with vat life.

Unless you plan on re-designing the printer and manufacturing your own vats, I do not see FL changing from the PDMS layer to anything else.  It works.  It does take an understanding, patients and sometimes $$ but it works.  It is actually a good option in my opinion.

I do not think FL wants customers changing out the PDMS layer.  This is why vats are sold ready for use.  B9C sells vats customers have to apply a PDMS layer to.

For what it is worth, I would compile an order of a few vats, maybe a build platform or 2 and some resin and get yourself some consumables.  All have a life expectancy.  They all will need to be replaced.

Sorry to be the one to enlighten you on this.  But if others chime in, I am willing to bet they will agree including the Formlabs team.

Thanks, David.



The hazing or fogging of the PDMS can happen after 30-40 prints or even after 1 print. It all depends on what happens during the prints.

If you print in one spot often, without letting the PDMS breathe a little, you are almost guaranteed that spot to get hazy.

If the print fails early on and the resin gets cured over and over, you will almost always get left with a foggy spot where the print was. This can be accelerated when using 3rd party resins that cure too hard and fast for the form1 (from personal experience ;))

The best property of PDMS is also it’s “Achilles heel”. The PDMS is a gas permeable membrane, so it takes on oxygen on the top layer and the oxygen prevents the thin layer of resin from curing, so that you can peel off the part. When the resin cures, there may be other gases that are created (I’m not a chemist, so it’s just a theory) and they saturate into the PDMS and this can slowly degrade the “non-stick” ability and eventually fog up the layer.

As I’ve posted before, “massaging” the pdms layer not only mixes the resin and gets the pigment off of the layer, it also lets the PDMS get oxygen back into the layer. That’s why I put slight pressure when scraping with the spatula. So far, I’m still using my original 2 resin tanks by doing this and there only a few spots that are damaged/foggy because of badly failed prints earlier on when I was learning the machine.

So do the scraping and the “pdms massage” before every print and sometimes even after for preventative measures, and you will increase the life of your tank.