How to Restore your VAT!


The primer is not necessary actually. There is no other way to know than trying so I ordered some and we will see.
I saw a thread on diy sla printer where someone used this and it seems to work.
For me it would be way better as the other options are not available in Canada, only in the US and cost a fortune in shipping, the price is the same or more as the product itself.


I got a hole in the silicone and the peo-resin baked a little bit into the acrylic. It won’t come off the acrylic easy at all. What would dissolve it without ruining the vat?

I suppose I could just go ahead and scratch the acrylic and get the resin off. Then use the novus plastic polish?


It seems I tore a whole in my PDMS layer because there was too much pressure between the build plate and the PDMS. So when the layer peeled away on the first couple of layers this created too much suction damaging the silocone. So main reason was improper leveling height. Second problem 8mm brim for the base of the supports was too large.


Any Idea if this would fit in the Moai? Apparently they can’t keep up with the demand. I should change professions and go into the glass vat business.


Mine has done that and the only way was to scratch it off and then polish it


Good news I received and tried the solaris silicone :
It works great, I calculated 68g to be the same height as my original pdms layer.

So it is a 1:1 ratio part A and part B and the pint kit should cover at least 13 recoats.
The pint kit comes with the primer so no need to buy separately, though I don’t know if it is included in the gallon kit.

It cures in 24h. You apply the primer 1 time, let it dry, wipe it. Do it a second time.
Then you pour the silicone, I don’t think the primer is necessary but it can only help.
I suggest mixing more and then put the vat on a scale and pour 68g because you lose some in the process (leftover in the cup etc).

There are several re-sellers of Smooth-On over the world so you can get it in maybe more countries than the ML Solar and Sylgard.
In Canada you can order here :


“Ultra-transparent Solaris® provides excellent UV resistance yet allows maximum transmission of light.”

What does it mean when it says “UV resistance”? It could mean it blocks UV light or it could mean this silicone doesn’t degrade from UV.


It means that it doesn’t become yellow with UV exposure, so yes doesn’t degrade.


Hi FlorenceA,

How did you go with the Solaris? It looks like it might be the only option in Australia aswell.


Like I said earlier, it went very well and I tested since on several huge prints. I’ve recoated 2 vats with it and here are some more tips.
I would recommend mixing more like 40g of each part, total 80g and pour 68g as to avoid the bottom of the cup as it is not as well mixed and will cure clouded.
They recommend mixing for 2-3 min in one cup, then pour in a second cup and mix again, it helps too.

The primer helps keeping the pdms layer fixed in the VAT but it is harder to remove, it doesn’t go off in one part if you applied the primer. But with alcohol it is easy to remove and was worth the extra adherence.
If you don’t want to clean the VAT with alcohol I don’t recommend the primer.


Thanks, I’ll give it a try


how about a note on how to prevent pdms ripping… after 10 or so prints I got a small rip on position A (was a bit disapointed, but figure that how it works, it was bound to happen)
… I continued on position B, works fine…

  • is it up to levelling, if it’s too tight or too loose? I went for a half turn, would a quarter turn work better…

-I’m loving the printer so much, so all the hassle is worth it, give me more directions please…

  • also what is the chemical compound of the pdms, maybe I can ask around the local industrial companies if they have something available… must print everything


In most cases I do believe that too big of a pull on vat causes rips and failures of PDMS. Try to reduce support structures that are too big and creates too much suction.


Well, after 400ml of resin,and only 10 prints of various sizes, my PDMS pulled off the vat;-(

I think partly as there is too much suction- but after the first few base layers, doesnt any unwanted ‘pressure stress’ even out as the bed lifts anyway ?

The how-to video I saw suggested a 2mm thick base on a model, Im wondering if I should stop using a solid base and use a 2mm base on the supports only, might this help ?

how long are people finding their base last ?
( I did think Id get more life from it sadly…)


also , what are the technical reasons for using PDMS ?

I might know of an alternative…:wink:


I make jewelry and for the simple rings I raise them 6 MM from bed and do a single 1.5 mm post with a 3 MM at the bottom. The 3 MM goes to the bed plate. I study a model and visualize the print as being printed then I apply the needed min. in order for it to stick to the build plate and with the least effect on the PDMS. Also change around your printing that will allow the PDMS bed to last longer. I print about five hundred rings before I need to replace PDMS layer. Also there are other materials that can be used Teflon, glass and a few others that are mentioned here.


it would be an interesting bit of research to see if there was a way to work out a direct link between the surface area of the support Vs the peel resistance of the resin layer.

So, having a massive support area = " at least it sticks" but reduces the PDMS life.
What if software works out the largest surface area of the model that will occur in a single slice. This would give the largest needed support strength to hold it to the plate, without overkill .
Also, I wonder if its possible to pre cure a first layer of resin, away from the PDMS tank, that is then mechanically clamped/ pre-loaded to the platform…say a sheet of ‘green’ resin 3mm thick. Clamp that to the platform, and then the printer just carries on as if it had printed the support base already?


I think I got a rip (rest in piece :confused: ) with this one… so less of the support on the aluminum base, or less supports overall?
If you make a bit taller support does it act as a damper maybe? The ones on the pic were 1mm 600 mm height of print object (without supports - so far this size works for me)
…around 8 holes all

  • also any alternatives to the alternative - the shipping cost on the first one was more than the price of the pdms…
  • the other link didn’t work


I use 2mm bases but the problem is when you have dense support you tend to merge those bases. Its fine if the piece is small - but when the part is larger you end up with a large base anyway.

Whats interesting is the formlabs software generates a big old thick solid base for prints - so either they have a better way of beating suction (doubtful) or they care less about ripping the pdms


Having massive support area and surface area does not increase the print success rate and can often cause a problem. When the print is peeling, there is a force pulling down, and the larger surface will dramatically increase the force the could lead to failure or bad layers.

interesting thought on pre-curing, it may introduce too much of layer lines and also causing bonding issue that leading to

PDMS layer’s elasticity concealed a lot of potential imperfections from manufacturing and installation. It is the reason why with Moai or most SLA bottom printers, you don’t try to level at a precise height, but rather pass a threshold and let PDMS does its magic.