Baking sheet silicone seals

[bt1]

Howdy,

Changed the glass still over to silicone baking sheet seal a few weeks back, from cork...which wasn't pure cork turned out to have that nitrated shit in it and was giving off flavours. Note of caution pure cork aint always pure cork...ask what it glued/combined with!

So I've read a bit lately bout the small volume of acetones we produce in the fores part of the run chews up the gaskets...my glass still is only 5 runs old so have no measure...

Any one got silicone seal of this type that have done a few runs?

love to hear from you...

all sealed up
bt1

[Brendan]

Hey bt1,

I haven't posted this yet, but have done some controlled experiments with different materials and took lots of photos.

I tested silicone baking sheet, silicone tri clamp seals, and EPDM seals...in Heads, Methanol and Acetone.

All I can say is the silicone does not do well with the acetone ESPECIALLY the red/coloured baking sheet stuff :naughty:

I'll get it uploaded tomorrow :handgestures-thumbupleft:

[baldoss]

Any more info on this Brendan? I've got a cork seal that I was considering replacing with something else, namely silicone, but sounds like there are more factors at play...

[googe]

He always gets his time frames messed up baldy, 1 day = 3 and 6 weeks = umm lets not go there :laughing-rolling:

[bt1]

Googe ...

there's no building required here to mess it up...

bt1

[Brendan]

Haha that is funny Googe, but fuck the lot of ya :teasing-neener: I've been busy with 'life'.

Righto, I'll get the pictures together now and get it sorted :handgestures-thumbupleft:

[googe]

Tthats a fair call lol. I'm really looking forward to these results, I have a business idea using. Silicones and the such.

[Brendan]

Tthats a fair call lol. I'm really looking forward to these results, I have a business idea using. Silicones and the such.

I'd put your money elsewhere Googe...

[MacStill]

yeah a soft PTFE would be the ducks nuts :handgestures-thumbupleft:

[Brendan]

yeah a soft PTFE would be the ducks nuts :handgestures-thumbupleft:

:text-+1: But where are they??

[MacStill]

I tried, believe me I've tried.

The supplier I'm dealing with "is looking into it"

[Brendan]

I have recently been doing a bit of research into the chemical resistance of common materials that home distillers use in their equipment.

After thinking that silicone was completely safe, I read on Cole Parmer's Site, and ‎Silicone Chemical Resistance Chart @ http://www.cicoil.com/pdf/ChemC2.pdf ...all experiments point to Silicone being fine for ethanol & methanol, but completely unsafe in ANY manner for use with acetone (even at room temperature).

Considering foreshots consist of a high percentage of acetone (don't they?), I decided to conduct an experiment myself.

DISCLAIMER: I conducted this experiment for myself at home. It's not done in a science lab, and I'm not preaching to everybody that my results are conclusive for you...but they are for me :snooty: Make your own mind up.

EXPERIMENT

I took material samples of:
1) Silicone Baking Sheet (Red one from Big W)
2) EPDM Tri-Clamp gasket
3) Silicone Tri-Clamp gasket

These samples were soaked in:
1) Mixed Early Heads/Late Tails
2) Methylated Spirits
3) Acetone

Samples:

S1.JPG

Liquid testing media:

TESTSETUP.JPG

Samples suspended in media:

S2.JPG

[Brendan]

RESULTS:

Time = 0 Hours

No immediate change to any of the solutions upon placing the samples into the liquid media.


Heads/Tails

S3.JPG

Methylated Spirits

S4.JPG

Acetone

S5.JPG

[Brendan]

Time = 90 Minutes

Easily noticeable change of the silicone baking sheet in the Acetone, as well as a very (extremely) slight change in the silicone tri-clamp seal in the Acetone. The EPDM seal in acetone showed no change.

All samples in the Heads/Tails, and Methylated sprits showed no change.

In all pictures, silicone baking sheet is on the left, EPDM in the middle, and silicone tri-clamp seal on the right.

Heads/Tails

S9-90.JPG

Methylated Spirits

S8-90.JPG

Acetone - have provided both HDR and normal resolution of the image to better show the colour change

S6-90.JPG

S7-90.JPG

[Brendan]

Time = 3 Hours

Extremely noticeable change in the silicone baking sheet in Acetone, as well as a slight colour change with the silicone tri-clamp seal in Acetone (would describe as the faintest 'milkiness' has tainted the solution). EPDM shows no change in Acetone.

All samples in the Heads/Tails, and Methylated Sprits showed no change.


Heads/Tails

S13-3H.JPG

Methylated Spirits

S12-3H.JPG

Acetone -have provided both HDR and normal resolution of the image to better show the colour change

S11-3H.JPG

S10-3H.JPG

[Brendan]

Time = 8 Hours

Extremely noticeable change of the silicone baking sheet in Acetone, and colour has got darker. Silicone tri-clamp seal in Acetone does not seem noticeably different from the 3 hour mark, but still off colour from the starting point. EPDM shows no change in Acetone.

All samples in the Heads/Tails, and Methylated Sprits showed no change.


Heads/Tails

s16-8h(2).JPG

Methylated Spirits

S16-8H.JPG

Acetone

S14-8H.JPG

S15-8H.JPG

[Brendan]

Time = 24 Hours

Extremely noticeable change with the silicone baking sheet in Acetone, colour is very dark (likened to an oaked spirit). Silicone tri-clamp seal in Acetone still shows no change since the 3 hour mark, but slightly off colour from starting point. EPDM seal still shows no change in Acetone.

All samples in the Heads/Tails, and Methylated Spirits showed no change.


Heads/Tails

S20-24H.JPG

Methylated Spirits

S18-24H.JPG

Acetone

S17-24H.JPG

S18-24H(2).JPG

[Brendan]

CONCLUSION:

As predicted by the chemical resistance charts, Silicone showed extremely poor resistance to Acetone. This effect was a lot more pronounced in the silicone baking sheet from Big W. Although it probably had a lot to do with the colour dye used in the material, it demonstrated clearly the extent to which the silicone was broken down into the Acetone solution.

Also inline with chemical resistance charts, EPDM showed complete resistance to Acetone, and all samples showed complete resistance to Ethanol and Methanol compounds.

It should be noted with this experiment that industrial 100% Acetone was used for the test. After I do a cleaning run through the bubbler, I am going to collect and hold onto the foreshots, and test the silicone in that to gauge the extent of the breakdown in comparison with the industrial Acetone.

Another point to note is that these tests were conducted at room temperature, while an operating still will be handling vapours at 70+ degrees celsius, which is only going to amplify/speed up the process of chemical breakdown.

I did not test any teflon based material (PTFE), as I only had access to plumber's tape. But seeing that chemical resistance charts list it as perfectly safe, and all data from this experiments concurred with those charts, I can only assume that this material would be acceptable.

I can conclusively say for myself that I have verified the characteristics of silicone in these compounds, as stated by chemical resistance charts, and will be looking to change out my own seals from this material.

The next question to ask is 'Would this leeching have any effect to the distillate if only in the upward vapour path?'...'Can a leeched chemical like this carry on upwards with the pure ethanol vapour?' Either way, it should definitely not be in the downward path or in contact with distillate being collected.

Thanks for reading :handgestures-thumbupleft:

[Brendan]

I just realised this thread was in the "Plated Column Stills" section...

I was just posting the experiment in here to follow in line with the thread title.

If any mods want to move it to the appropriate materials/accessories areas, feel free. :handgestures-thumbupleft:

[googe]

Good experient mate :handgestures-thumbupleft: ive used EPDM since I started this and there pretty much perfect still, just a little flatter from clamping.