# Glass bottom tray Form 2 **URL:** \ **Category:** Feature Requests & Ideas\ **Created:** [October 3, 2016, 3:47am UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850 "2016-10-03T03:47:13Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Cobaltred](https://avatars.discourse-cdn.com/v4/letter/c/ce7236/32.png) [@Cobaltred](https://forum.formlabs.com/u/Cobaltred)\ **Post date:** [October 3, 2016, 3:47am UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/1 "2016-10-03T03:47:13Z")
I have only bought three trays and will be using them forever, I wedged a razor blade under the acrylic bottom and gently hammer the back of the blade to start a small unglued area then advance the blade a bit further hit the back of the blade until the acrylic is all unglued. Then replace the bottom with a 1/16 ‘’ thick piece of regular glass or you can use bro silica glass. clean with sandpaper the ledge on the tray and glue the glass in place with gorilla epoxy on the edges. Now buy some sly guard 184 and peel the old silicone layer out and use an accurate scale to get the right amount for me 92 grams to 9.2 part B seems to work perfect. Mix very thoroughly in a regular plastic cup and pour as much as you can into a level tray then wait about ten minutes and put a clean sock on the end of a hair dryer for a filter turn the hair dryer on with heat and run for a few seconds to heat the air and to blow out and particles that may happen at the start and swipe the hot blowing air over the top of the tray and all bubbles will disappear. Set a clean piece of paper over the top to prevent dust from landing on the uncured silicone and let sit for two days. I would like for Form labs to sell there trays without the plastic bottom it would be much easier and trays would not have to be consumables just the silicone layer, About $12 for a new tray not $60 I would also like to see Form labs sell fresh empty cartridges as well. Thanks Buddy. ---
**Author:** ![CraigBroady](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/craigbroady/32/6106_2.png) [@CraigBroady](https://forum.formlabs.com/u/CraigBroady)\ **Post date:** [October 3, 2016, 2:19pm UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/2 "2016-10-03T14:19:03Z")
Many DIY-focused users have been replacing the silicone on their tank for a while. What have you found is the benefit of replacing the acrylic with glass? ---
**Author:** ![Cobaltred](https://avatars.discourse-cdn.com/v4/letter/c/ce7236/32.png) [@Cobaltred](https://forum.formlabs.com/u/Cobaltred)\ **Post date:** [October 3, 2016, 2:56pm UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/3 "2016-10-03T14:56:47Z")
When then old silicone layer is spent, just peel out and instead of having to clean perfectly clear the acrylic which is difficult to do. You can clean the glass on both top and bottom very easy, then pour a new layer and done. Have you ever tried to clean acrylic perfectly clear, it scratches easy and do not touch with anything or it will show. god forbid you get and smudge of resin on the acrylic sticks like crazy. Buddy. ---
**Author:** ![Cobaltred](https://avatars.discourse-cdn.com/v4/letter/c/ce7236/32.png) [@Cobaltred](https://forum.formlabs.com/u/Cobaltred)\ **Post date:** [October 3, 2016, 3:01pm UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/4 "2016-10-03T15:01:06Z")
Forgot to mention one other thing and that is that the laser is currently going through a thickness of about 5/16" acrylic. with the 1/16" glass less solid material to go through 5/16 " is way overkill on the bottom of the tray. Buddy. ---
**Author:** ![dunginhawk](https://avatars.discourse-cdn.com/v4/letter/d/db5fbb/32.png) [@dunginhawk](https://forum.formlabs.com/u/dunginhawk)\ **Post date:** [October 3, 2016, 3:02pm UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/5 "2016-10-03T15:02:48Z")
I think the biggest benefit of the glass is that it doesnt scuff, scratch etc as easily as acrylic… I know the folks that use a zakvat on the form1+ see the difference. You can use glass cleaners, or simple green, etc… thats a bit benefit to me. ---
**Author:** ![KenCitron](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/kencitron/32/1741_2.png) [@KenCitron](https://forum.formlabs.com/u/KenCitron)\ **Post date:** [October 4, 2016, 2:26am UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/6 "2016-10-04T02:26:07Z")
Why not use a thicker piece of glass so you use less silicone? ---
**Author:** ![dunginhawk](https://avatars.discourse-cdn.com/v4/letter/d/db5fbb/32.png) [@dunginhawk](https://forum.formlabs.com/u/dunginhawk)\ **Post date:** [October 4, 2016, 2:27am UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/7 "2016-10-04T02:27:13Z")
has nothing to do with the amount of silicone… The glass fits snug to where the acrylic used to for him… it just doesnt protrude as far down… so net net is same silicone if i understand this right 🙂 ---
**Author:** ![3DTOPO](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/3dtopo/32/6361_2.png) [@3DTOPO](https://forum.formlabs.com/u/3DTOPO)\ **Post date:** [October 8, 2016, 1:50am UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/8 "2016-10-08T01:50:01Z")
> [@Cobaltred](#): > > Then replace the bottom with a 1/16 ‘’ thick piece of regular glass or you can use bro silica glass. Do you have precise measurements of dimensions of glass you used? > [@CraigBroady](#): > > Many DIY-focused users have been replacing the silicone on their tank for a while. What have you found is the benefit of replacing the acrylic with glass? Besides the other improvements mentioned, I have read that there is a noticeable improvement in print quality when using glass. ---
**Author:** ![Cobaltred](https://avatars.discourse-cdn.com/v4/letter/c/ce7236/32.png) [@Cobaltred](https://forum.formlabs.com/u/Cobaltred)\ **Post date:** [October 9, 2016, 3:01am UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/9 "2016-10-09T03:01:39Z")
No, you just have to measure the rectangle and I think it is a rectangle not a square and make the glass a bit smaller. I made one to tight first time and it did not seat all the way down, had to break the glass to remove and started over, no big deal if you mess up. you also do not have to smooth the cut edge although I did. B. ---
**Author:** ![wadewilliams](https://avatars.discourse-cdn.com/v4/letter/w/c4cdca/32.png) [@wadewilliams](https://forum.formlabs.com/u/wadewilliams)\ **Post date:** [December 8, 2016, 3:49pm UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/10 "2016-12-08T15:49:59Z")
Cobaltred, We have recently switched a couple Form 2 trays to glass with the Sylgard silicone layer. However, we have had problems with the build platform sticking so much that the motor cannot overcome the force and move the platform up between the layers of the build. The cured resin is adhering properly to the build platform. We have measured the distance between the top of the tray and the Slygard–it is only 0.06mm higher than the FormLabs PDMS layer. Yet we have adjusted the Z Height by up to 1.7mm and the build platform still sticks during the build. Have you (or anyone else) seen such problems? Thanks, Wade ---
**Author:** ![David\_Maillot](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/david_maillot/32/6489_2.png) [@David\_Maillot](https://forum.formlabs.com/u/David_Maillot)\ **Post date:** [December 8, 2016, 4:41pm UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/11 "2016-12-08T16:41:38Z")
I recently bought a Z vat, which alaso have a glass bottom… an had the same problem. My Z axis is set a 1.7mm now and everything is working fine. Let see if it really last longer now. ---
**Author:** ![Cobaltred](https://avatars.discourse-cdn.com/v4/letter/c/ce7236/32.png) [@Cobaltred](https://forum.formlabs.com/u/Cobaltred)\ **Post date:** [December 9, 2016, 1:44pm UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/12 "2016-12-09T13:44:10Z")
Personally I have not had any problems with this method, one thing could be to make sure you let the silicone cure for at least the full 48 hours. I am sure you know this though. Make sure you mix very well. Also by accident I made one tray about 10 grams to full and that tray I had a similar problem. I reduced my measurement to what I posted in the first post 92 to 9.2 grams and that has worked for me just fine, however I believe the layer needs to be the same or slightly lower but not higher, it is possible you will have to reduce the measurement a bit lower and try that.Remember your measurement also includes material that gets left in the plastic mixing cup and I really scrape all I can get out so that means some people will not take the time to scrape all into the tray. Let me know. The glass trays do not last any longer than a normal trays just because of the glass, it is just the cost,ease of cleaning and convienience of having fresh trays at hand. I f anyone wants to reduce the cost of printing than the resin is worst offender not the tray.You are the only one to chime in on your experience, I would like to here from more people so that a good universal recipe could be adopted for all, I am only one person.Thanks. Buddy ---
**Author:** ![wadewilliams](https://avatars.discourse-cdn.com/v4/letter/w/c4cdca/32.png) [@wadewilliams](https://forum.formlabs.com/u/wadewilliams)\ **Post date:** [December 14, 2016, 1:06pm UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/13 "2016-12-14T13:06:09Z")
Thanks both replies. David, our trays came from Zak at Z-Vat as well. He is in the loop on this issue, and we’ve been trying to work through this to find a solution. He has offered to replace/refund the trays if we can’t get these working. Cobaltred, thanks for your info. We may just have to reduce the silicone layer so it’s not higher. I’ll try to keep everyone posted. ---
**Author:** ![David\_Maillot](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/david_maillot/32/6489_2.png) [@David\_Maillot](https://forum.formlabs.com/u/David_Maillot)\ **Post date:** [December 14, 2016, 2:11pm UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/14 "2016-12-14T14:11:50Z")
I have abandonned the z vat a few days ago, build Platform was sticking again… I tried to move the Z axis to 1.8, but then the resin wouldn’t stick to the build Platform. Ijust don’t understand it…the only thing I noticed is that it wasn’t sticking at the beginning of the print but reaching layer 17 or 18 ( printing 2mm support@50). I will get in touch with Zak… ---
**Author:** ![Cobaltred](https://avatars.discourse-cdn.com/v4/letter/c/ce7236/32.png) [@Cobaltred](https://forum.formlabs.com/u/Cobaltred)\ **Post date:** [December 15, 2016, 4:10pm UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/15 "2016-12-15T16:10:29Z")
For what it is worth I have not adjusted my z at all. B. ---
**Author:** ![Volguus](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/volguus/32/7962_2.png) [@Volguus](https://forum.formlabs.com/u/Volguus)\ **Post date:** [December 16, 2016, 2:17pm UTC](https://forum.formlabs.com/t/glass-bottom-tray-form-2/9850/16 "2016-12-16T14:17:18Z")
I just had a thought - does an equivalent glass part to the Formlabs acrylic part have a different level of UV transmission and index of refraction? The former may certainly affect the print sticking/not sticking issue, but I wonder if the latter can be tested. Since the Form laser beam originates from a central point (correct me if I’m wrong), a tray window with a higher refractive index (like glass vs, acrylic) would result in a print that could be slightly larger on the X and Y axes. I know the Form2 lets you easily compensate for that, but has anyone discovered whether it actually happens or not?