Waterproofing ETC chamber

ClarityNL

Hi everyone,

We are trying to make our own ETC chamber, but we are in trouble trying to waterproof the electrode holes. We tried plastic kit around it, rubbers with plastic kit, rubbers without plastic kit, parafilm.. but the chamber keeps leaking. The plastic kit does not seem to stick to the chamber. Has anyone encountered the same problem? Hope you can help me out. A photo of our setup is included, after several tries we ended with the parafilm (still not waterproof).

Esther

http://www.mijnalbum.nl/Foto650-NUPZ4MXV.jpg

liz_kritzer

I use Quick-Setting Epoxy from Radio Shack (a cheap two-part epoxy) to seal all the components of the chamber. Even though it says "quick," I still let it cure overnight before getting the chamber wet again. I have not had any leaks since completely sealing all joints with this epoxy.

LauraLynch

Oh, the leaking thing. The brains I have fried because of leaky chambers!

I have used several different epoxies. I've had reasonable luck with Hardman Double/Bubble epoxy (available on Amazon), which lasts for a week or so before it starts to harden too much and pull away from the joints. When it turns the same color as a finished brain, it's time to re-glue. It cuts away easily when it's ready to be replaced.

Now I'm trying Devcon plastic welder (available from McMaster-Carr) for the first time. It doesn't appear to adhere to the Nalgene container as well. I've had to put on several layers and reinforce it (see below). I don't know how long it lasts; I'm in my first run with it now.

For on-the-fly reinforcement, I'm using KwikSil (from World Precision Instruments). This epoxy sets within minutes and is very good for stopping small leaks. It's not very strong, though; it peels away easily. Don't use it for primary adhesion.

nparker327

Score everything!! The Nalgenes surface is much too smooth for epoxy to readily form a good bond. I usually etch the surface with a razorblade for about 10 minutes before applying any epoxy. This has been the game changer for me. (I am also using the Devcon plastic welder and have not had a leak in over three weeks)

N

vinL

Has anybody had an issue with the chamber leaking from the threads of the Nalgene? All the other holes (input/output/wires) don't leak, but the pressure builds up and leaks from the threads.

Kristin_Engberg

Try adding some Teflon tape to the threads of the Nalgene. It may help with this leaking.

AReady

We've been able to prevent leaking from the threads by making a poor man's O-ring with silicone grease. We had a lot of issues with Teflon tape initially because while it would work for one sample, after we switched to a new sample we would be unable to recreate the seal.

vinL

Thanks for the suggestions. We've tried Teflon tape and also actual o-rings, but still have leakage along the threads. Have not tried silicone grease though, so that's worth a shot.

LauraLynch

Sometimes it's just a bad jar-lid combination. I had that happen to me once; I tossed it and pulled another set out of the bag.

AReady

I've had bad jar-lid combinations with a number of sets from the same bag - one reason I'm looking forward to seeing where that 3D printed chamber discussion goes.

vinL

Much thanks. Yeah, I think we might be having custom-made chambers as well.

LabDaemons

This is copied over from another thread, but take a look at photos of the electrode assembly and insertion (http://flic.kr/s/aHsjH4vnfk) we developed for a 3D printed chamber. The goal was to ensure a water-tight fit while maintaining proper alignment and allowing easy removal & replacement of worn electrodes.

After testing various systems, the best performance was achieved using nested silastic tubing and a PVC wire cap.

The 0.5 mm platinum wire is initially inserted into a silastic tube (0.6 mm i.d. x 1.0 mm o.d.).

This is then inserted into a larger silastic tube (1.0 mm i.d. x 2.0 mm o.d.).

This is then inserted into a PVC cap that serves two functions: 1) maintain electrode alignment; 2) provide a convenient point for handling the electrode assembly.

The electrode insertion points in the 3D printed chamber are sized to give a water-tight fit when the electrode assembly is firmly in place (you really gotta squeeze them in there). The back-pressure from inside the chamber actually squishes the silicone/PVC up against the walls of the electrode insertion channel and helps make a good seal. If you do get a leak with this method there are many really good adhesives for ceramic (easier to bond than Nalgene bottles) that should seal the electrode assembly in place.

KatherineHolzem

Leaking has been a major problem for our setup as well. Thanks for all of the great ideas.

We have had the best luck with Sylgard 182 when we cast it on the inside of the base and the lid. When that fails, or preemptively anticipating that it will eventually fail, we also use PC Products Auto Bond epoxy (available on amazon), which is flexible when set and relatively fast-curing. I agree with @LauraLynch above that KwikSil can work in a pinch to patch up a small leak, but that it doesn't bond well to the Nalgene container.

ClarityNL

We solved our water problem, we inserted little rubber stops at the spot where the electrodes came out, now the electrodes are isolated and waterproofed by them... Thanks all for the effort of helping. Our chamber is ready for use!
@vinL, we did not experience any trouble with leaking through the threads now the rest is waterproof. We got lucky and had a good jar-lid combi!

LabDaemons

@ClarityNL glad you got the leaks under control! The rubber stops serve much the same purpose as the silicone tubing + PVC cap in our setup. For long term use you should check the stability of your rubber (not all rubbers are the same) against the reagent list for the ETC solution.

ClarityNL

@LabDaemons thanks for the tip! I think these will be resistant, but we'll keep an eye on it.