HowTo: Electronics – Encapsulate electronics waterproof with epoxy

During the construction of a chain of lights, I was faced with the problem of how to get this chain of lights waterproof.

Ultimately, I built the electronic components, which must not be exposed to moisture, in a 3D printed transparent housing. In order for them to be finally waterproof, the electronic components had to be encapsulated with potting compound.

This potting compound is transparent and does not conduct electricity. In addition, it is liquid at the beginning and then hardens later. So it is perfect for protecting electronic components from contact with water.

Of course, this does not only apply to fairy lights. Ultimately, other electronic components can also be protected from contact with moisture in this way.

I have described how I did this in the following article.

Safety instructions

I know the following hints are always a bit annoying and seem unnecessary. But unfortunately, many people who knew it "better" from carelessness lost their eyes, fingers or other things or hurt themselves. In comparison, a loss of data is almost not worth mentioning, but even these can be really annoying. Therefore, please take five minutes to read the safety instructions. Even the coolest project is worth no injury or other annoyance.

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Required tools:

Required material:

Prepare the workplace

Since working with epoxy resin can quickly become quite dirty or sticky, you should prepare your workplace accordingly.

You should cover your work surface for this. It is easier to throw away the old newspaper later than to remove the (possibly even dried) epoxy resin from the work surface. 🙂

You should also ensure there is a sufficient supply of fresh air. If possible, work outside or at the open window.

You can also support the ventilation of your workplace with a fan.

This means that any vapors that may develop cannot be inhaled or are at least heavily diluted.

Safety precautions

The safety precautions are at least as important as the preparation of the workplace.

This includes at least

  • Protective gloves
  • safety goggles
  • Smock
  • a suitable protective mask

You should prepare yourself so that the epoxy cannot come into contact with unprotected areas of skin or even in the eyes.

Prepare the casting mold

Depending on the structure of your project, you should prepare your casting mold for filling in the epoxy resin.

In this example shown, the LED elements of the 12V light chain are potted.

As you can see, the individual LED strips protrude…

… from the casting mold.

Since you just want to completely encapsulate the electronic parts in epoxy (because this is the only way to protect them waterproof) you should now ensure that the parts in question are completely enclosed by epoxy later.

The solution to this problem is to fix the electronics in the casting mold so that they are later completely covered with epoxy.

Often it is enough to fix the electronic components (here the LED strip) with a little hot glue in the casting mold so that it no longer protrudes from the casting mold.

So put in the necessary places …

… some hot glue on …

… and fix the LED strip or all electronic components that need to be potted waterproof …

… in the casting mold.

The electronic components should then be so deep in the mold …

… that no part peeps out of the casting mold.

Another view.

Another view.

Prepare the casting compound

After you have prepared your workplace and the potting compound, you can now prepare the actual potting compound.


Put on protective equipment!

Potting compound often consists of two components, which have to be mixed in a certain ratio.

Read carefully the instruction manual, which is printed on the bottle.

As soon as you have read the instructions on the bottle completely …

… you can prepare the casting compound.

Mix the two liquids in the correct ratio. A kitchen scale can be very helpful here.

But then of course also make sure that these kitchen scales either do not come back into the kitchen or are appropriately packaged / protected so that no residues of the potting compound can come into contact with food or drinks.

If you have mixed the two liquids you should mix them evenly.

For example, an old wooden stick from an ice cream or a wooden toothpick is suitable. You can easily dispose both after use. (Make sure, however, that leftovers may not always be disposed with household waste.)

Pick up potting compound

I often find it difficult to fill in the prepared casting compound. However, in my opinion there is one good tip that makes the whole thing much easier and cleaner.

Instead of pouring the potting compound directly from the “preparation vessel”, you can also draw the potting compound into an old syringe.

Draw as much epoxy as you need into one …

… appropriate syringe

Fill in the casting compound

Thanks to the above-mentioned tip, you can now pour the potting compound into the potting mold relatively easily and in good doses.

Now you can simply pour the potting compound from the syringe into the potting mold.

So you can check that the potting compound is filled evenly everywhere and is well distributed.

Another view.

If you have filled in enough potting compound, you should now check again that the electronic components are covered by potting compound everywhere.

Another view.

Another view.

Another view.

Another view.

Another view.

Another view.

Another view.

If needed close the lid

Whether this step is necessary depends heavily on how your casting mold is constructed.

In the example shown here, the cover of the LED elements is so close to the encapsulated LED elements that it will probably not be able to be put on correctly later.

That’s why I recommend putting it on here when the casting compound has not yet hardened.

Another view.

Another view.

Another view.

Have fun with the project

I hope everything worked as described. If not or you have any other questions or suggestions, please let me know in the comments. Also, ideas for new projects are always welcome. 🙂

P.S. Many of these projects - especially the hardware projects - cost a lot of time and money. Of course I do this because I enjoy it, but if you appreciate it that I share these information with you, I would be happy about a small donation to the coffee box. 🙂

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