Public Lab Research note

Waterproofing the Riffle

by pdhixenbaugh | July 09, 2018 21:10 09 Jul 21:10 | #16670 | #16670

What I want to do

Hi Y'all

Sorry about my disorganization. I am going to next investigate waterproofing a wire through a plastic bottle cap, in preparation for my Riffle Deployment. I have verrrry limited experience in this area. So, the two parts to this are:

  1. How to make the hole through the cap (i'm guessing a drill...)
  2. How to waterproof it (I'm guessing silicone sealant/goop)
  3. Where else to look for information ... ∞. Write a guide for how to waterproof a container for a Riffle/ other sensor, emphasizing low-cost, high-waterproofing, and simple deployments with known assumptions about depth/wear, etc.

My attempt and results

I used the public lab search to find stuff and I did find some links * Uses a rubber stopper (bung? $0.40) for better waterproofing and interchangability, but also you have to get piping to put through the stopper, and aquarium-grade sealant to stop it up. * found a lot of things that didn't work, but then seemed to find that a mason jar lid (on a plastic peanut butter jar container???) stayed watertight. So that might be worth investigating * Ed Mallon suggested a ~$10 PVC enclosure technique. * There is also a video with a method involving a toaster oven.

Questions and next steps

  • What else am I missing in my search
  • Are there already guides to this / people who I can learn from?

Why I'm interested

(I should really link my posts together -- teaching kids about how to ask scientific questions about their ecosystem health, and take measurements into their own hands.)


There's also been some discussion of leaving the device in an upside-down bottle outside the water, say with the bottle taped to a long stake, and taping the wires to the stake to go down into the water - could be simpler!

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@warren great suggestion! It rains a lot here so I'm somewhat worried about that too. Where can I find that conversation? Are there any inexpensive DIY moisture indicators to test how effective the setup is? (There was something we used in chem lab dessicators that changed color when it absorbed moisture.

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Hm, i can't seem to find it. i think it may have been buried in a comment thread somewhere!

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I think this page may have some on moisture sensing!

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I keep my eye out for old Nalgene bottles which are tough enough to survive rough handling and hydraulic pressure. The lids are also strong so they can be tightened securely and a hull penetrator will work well:

There are a few of these hull penetrators still available at the KAPtery:
And these look like a good deal:

For outdoor deployment on land where rising water will not threaten the enclosure, I have been using plastic peanut butter jars. The lids are not that strong, but hull penetrators work well on the nice flat top. See Figure 8 here:

If the peanut butter jar is protected or under cover, a hull penetrator might not be needed.


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