Hello there.
I'm currently working a little washing machine gadget that I want to make waterproof.
I decided to go with potting because it looks nice to me.
Now I was wondering, how much potting compund do I need to buy if I want to pot an Arduino Leonardo aswell as an 2.8" display?
Thanks for your help! 
It depends on the specific potting compound and it's properties.
If you need to know the volume, Put parts into a cup. Fill up with sand. Remove parts, measure how much sand you need to add to fill cup - then you know the volume that you do NOT need to fill with potting compound. Find your prefered case, measure internal size, calculate internal volume, look up specific gravity of the potting compound you want to use and calculate mass you need.
// Per.
Hello, thanks for your fast and precise reply.
I'll definitely do what you recommended when I find the time. Currently I just really need an estimate.
Is 100g too less for what I'm planning to do?
Questions:
When you say "potting the arduino" The use of the word "potting" congers up images of putting the arduino in some container and filling the container with resin of some sort. Is this what you have in mind?
Also you mention display is the display being potted?
Also, there's a big difference between waterproof (can survive under water) and water resistant (can be splashed without negative effects).
JohnRob
Hello, yes I do wanna cover my Arduino aswell as my display in potting compound.
As I said the gadget is built for a washing machine so it should be waterproof.
So, how much compound would I approximately have to use?
ThisIsMeRS:
Hello, yes I do wanna cover my Arduino aswell as my display in potting compound.
As I said the gadget is built for a washing machine so it should be waterproof.So, how much compound would I approximately have to use?
Now it sounds like you are going to not pot (cast) the parts into a solid block of resin - which it sounded like in your first post!
100g is plenty if you just want to give the boards a "conformal coating" - you usually buy it in a spray can, apply a few layers and the parts are protected against moisture and the occasional drop landing on the circuit board.
Look for "conformal coating" and polyurethane laquer.
// Per.
ThisIsMeRS:
Hello, thanks for your fast and precise reply.I'll definitely do what you recommended when I find the time. Currently I just really need an estimate.
Is 100g too less for what I'm planning to do?
If you do not have a weighing scale 100 ml of water equals 100 g,
Your potting compound should have a quoted specific density . You can measure the volume and use that to work out the required amount.
Do you really want to POT or just cover. The viscosity of the potting compound may be the key figure there.
Thermal considerations are also needed.
Provided the device is not immersed a conformal coating may be sufficient.
ThisIsMeRS:
Hello, yes I do wanna cover my Arduino aswell as my display in potting compound.
That may be a problem depending on your display.
White goods displays on the like of ovens and washers do not generally use that method.
For LCD displays the edges of the glass can be sealed though.
ThisIsMeRS:
Hello there.
I'm currently working a little washing machine gadget that I want to make waterproof.I decided to go with potting because it looks nice to me.
Now I was wondering, how much potting compund do I need to buy if I want to pot an Arduino Leonardo aswell as an 2.8" display?
Thanks for your help!
Perhaps you need to rethink the use of potting compound. First you will have to have the Arduino in an enclosure that cannot leak the potting compound. It is just as fluid as water and will find even invisible cracks and holes.
Second, you will never be able to download another program to the Arduino because the USB connector is now inside the enclosure and covered with potting compound.
Third, you will have to power the Arduino by wire, plus ground wire.
Fourth, potting will do no good if you have insulated, stranded wire going into the potting compound to connect to the Arduino. Those wires will wick water into the potted Arduino.
The best solution is polyurethane, as has been suggested. It can be applied with a small paint brush and connectors and such can be avoided. You can even use the polyurethane you get from a local hardware store.
Paul
ThisIsMeRS:
Hello there.
I'm currently working a little washing machine gadget that I want to make waterproof.I decided to go with potting because it looks nice to me.
Now I was wondering, how much potting compund do I need to buy if I want to pot an Arduino Leonardo aswell as an 2.8" display?
Thanks for your help!
Potting is usually unnecessary, creates a mess and makes modification or repair of a project almost impossible.
I would suggest instead using a waterproof plastic box (with a clear lid if you are going to be using a display) ... something like this:
(click the image for the link)
Of course, this may not be the size or type you need, it's just an example of what I'm talking about.
As far as potting compound, what will you use? Epoxy? Silicone? What durometer? One part? Two part? Curing time vs. working time? Will the compound shrink and damage the board? Will it release nasty chemicals as it cures and kill your board? How well does it insulate?
Lots of things to consider with potting compound, and lots of ways a one-off project can get screwed up by the wrong compound and/or the lack of experience with the particular compound you plan to use.
Take it from one who knows... stay away from potting compound. UGHHHHHHH!!!!!!!!!
Krupski:
Potting is usually unnecessary, creates a mess and makes modification or repair of a project almost impossible.I would suggest instead using a waterproof plastic box (with a clear lid if you are going to be using a display) ... something like this:
(click the image for the link)
Of course, this may not be the size or type you need, it's just an example of what I'm talking about.
As far as potting compound, what will you use? Epoxy? Silicone? What durometer? One part? Two part? Curing time vs. working time? Will the compound shrink and damage the board? Will it release nasty chemicals as it cures and kill your board? How well does it insulate?
Lots of things to consider with potting compound, and lots of ways a one-off project can get screwed up by the wrong compound and/or the lack of experience with the particular compound you plan to use.
Take it from one who knows... stay away from potting compound. UGHHHHHHH!!!!!!!!!
I concur with the enclosure option. That one includes a gasket to seal top and bottom.
Potting compound in the US is an expensive pain if only doing a few boards. There is a fairly large minimum quantity that you can purchase, then hazardous material charges. Then there is limited shelf life for most type of potting compound.
Paul
There are very many potting and coating compounds.
Most are expensive and unless you are familiar with their use experimentation could be rather expensive.
Spray on conformal may be the cheapest option.
All the washing machine boards i have seen however have none.
As do ovens , boilers and fridges.
Why do you think you need it. ?
Something else to consider, How much heat will the Arduino produce. Any heat that the regulator produces, will be trapped in the potting compound. Although the regulator is protected from thermal overload, you may find your Arduino is shutting down unexpectedly due to heat. Conformal coating or a watertight enclosure is the best route to go. The only things that I recommend that should be potted would be for safety reasons. Such as a electric toothbrush charger. The potting will keep it from shorting out if it is knocked over into the sink. For such devices the engineers calculate the heat generated by the device, and make sure that it is compensated for.