Introduction: Cotton Ball Bowl

By Shop Time
About: Come spend some time in the shop. I'm a hobbyist woodworker and professional computer geek in Northern California. I guess my projects will vary widely, and I have no clue what I plan to make next...

This is my cotton Ball Bowl. It's hard as a rock and looks like stone. Is that irony? I think it might be.

I've worked with cotton and resin once before on my cotton snowman ornament from 2014. It was always a material that I wanted to re-visit and showcase.

Most people who I show this to are surprised to learn it isn't stone. I think there are a lot of possibilities left for this material.

Step 1: Casting Cotton in Resin

I start with 140 cotton balls, 1/2 gallon of ArtResin epoxy and a silicone mold to hold it all.

I start by mixing up 12 oz of resin, just to see how far it will go. You never want to mix up too much resin at once. It cures with an exothermic reaction and too much resin in a small volume can easily overheat.

I then add a handful of the cotton balls and mix it all together like some nasty batter.

The mold is just to keep things all contained, but really there isn't much liquid for it to hold. Not like a traditional casting as the cotton just soaked it all up.

I add another handful of cotton and another 12oz of resin.

....ANNND IT'S GONE.

Add another 12oz!

Normally when you're pouring epoxy you CANNOT pour this much at once. Most epoxies in this confined of a space would cause a massive overheating and would boil over. Most manufacturers will tell you not to pour more than 6-8oz at a time. here, we're at 36oz.

Step 2: Resulting Cast

So, how am I getting away with this?
Art Resin is typically used for preserving museum-quality art and is formulated to cure over a 24-48 hours time. Due to the volume that I used, it cured rock hard in 3 hours. At the 2-hour mark I picked up the mold to move it and the bottom was crazy hot! Checking with the temperature gun I was just under 150* F

After 4 hours it is completely cured. (about 20 hours ahead of schedule) It's strange to pick up a very heavy, very hard block of cotton.

I then drilled a 5/16" hole in the center of the block for mounting on the lathe.

Step 3: Turning Cotton Balls Round 1

THIS IS AWFUL. It is one of the most difficult and grabby pieces I've ever tried turning on my lathe!

My whole bench was rocking and shaking and the shaving flying off, actually caused bleeding on my knuckles (which you can see in the video)

Here's why. The cotton balls soaked up the resin, but clearly, they needed more. There were so many holes and soft spots the bowl was just incredibly unbalanced on the lathe. Plus my lathe is pretty underpowered for this work (1/2 hp).

I also tried using carbide tools, thinking I would get a better cut. This was a mistake, and I pitched the whole bowl off the lathe and into the wall.

Step 4: Turning Cotton Balls Round 2

So, I took the bowl off the lathe, (actually it was already off...) and I mixed up another 4 oz of resin to fill in all the holes and soft spots.

Now, I was all out of Art Resin so I had to use another brand. I ended up using a marine epoxy called Total Boat. It seems to work well and cured hard in about 6 hours.

After it cured, I mounted the bowl back on the lathe and it turned like a dream!

Long shaving, smooth sailing and some really fun turning.

Lastly, I rounded over the rim and sanded the whole piece to 400 grit.

Step 5: Finished Piece

I'm very pleased with the outcome. It feels and looks a LOT like stone to me.

It is a bit hard to photograph. I only wish I could show it to each of you in person. The small bits of cotton that show through here and there really help to sell the illusion.

This is the snowman ornament I made in 2014. You'll notice that as the resin yellows, the marble facade continues. I think it almost gets better as time goes on.