[Adosia] has some interesting videos about their IoT platform controlling self-watering plant pots.  However, the video that really caught our eye was the experience in sealing up sensors that are going to be out in the field.  Even if you aren’t using the exact sensors, the techniques are useful. 

We would have expected to see potting compound, but that’s messy and hard to use so their process is simpler.  First, a few coats of clear urethane sealant goes over the electronics.  Next, heat shrink goes over the assembly.  It isn’t ordinary heat shrink though, instead it’s the kind that has heat-activated adhesive inside. 

If you haven’t seen adhesive-lined heat shrink, it is often sold as marine heat shrink — you can even find it under that name at Harbor Freight.  You also see this sometimes in tape form as heat shrinkable electrical tape. 

Heat shrink seems ubiquitous and commonplace, but it is actually a fairly recent and sophisticated creation.  Creating it usually requires radiation and sophisticated polymer chemistry, and it has only been available since 1962.  If you do try potting instead of this technique, our advice is to avoid the silicone and stick with a proper two-part epoxy.