Video
sign-in for video linkSummary - First Video
In this video, the creator is casting a bowl with wood pieces in epoxy.
When casting the epoxy and wooden pieces for the bowl, the creator is using a plastic bowl for the casting mold. In addition, he is using a wooden cylinder to fill the center of the bowl. The remaining space is filled with epoxy and several rough cuts of wood.
The use of the wooden cylinder offers a nice advantage. This material is going to be turned out when carving the interior of the bowl, and the wooden cylinder is less expensive than epoxy.
The use of a bowl for his casting container is also a nice cost savings technique. If one cast a cylinder the bottom curve of the bowl would need to be turned down. This would result in more material waste as well as more wood working effort to complete the bowl.
Overall, this is a neat plan for making a composite wood/epoxy bowl. Its espcially good if one is experimenting and looking to try out a few things while keeping their costs down.
Preping and Mixing
Once the creator has identified the wooden pieces that will go in his bowl, he fills the gaps with rice. This rice is then poured into a container to measure the volume of epoxy that will be needed for casting his turning blank.
Before pouring epoxy, a release agent is wiped into the plastic casting bowl. In this case, wiping it was done to keep from spraying the agent on the wooden cylindar has was already glued into the casting bowl (mold). He mentions that one can use a cooking spray as a release agent. If you're making a bowl that is expected to contact food, this is probably a wiser choice. Attaching elements that will be in the epoxy before applying a release agent is a bit risky. You certinal don't want the release agent to get on any of the parts that are in the epoxy, it would just interfere with the epoxy's bound.
To mix the epoxy, epoxy is pumped from a gallon jug, the pump is nice for dispensing the epoxy and hardner, but for larger volumes, its probably easier to just pour the resin/hardener directly into the mixing bowl.
This creator had some goood mixing techniques. First they measured the needed resin and hardener by weight. To eliminate any time pressure, the two halves were measured in separate bowls and then one was poured into the other.
Pouring a measured quantity from one mixing container into another will leave some material stranded, which means the carefully measured weights are inherently less accurate. But to compensate, the creator mixed the two materials, then poured the mix back into the other measuring container. This would essentially eliminate the volume error. Though it does use two mixing containers.
Pouring
After mixing the epoxy, the creator pours the epoxy over the wooden pieces in the casting bowl. As he does that, he realizes that he needs to hold down the wooden pieces, so there is a slightly chaotic moment while he tapes them down. Then it adds some mica powder to add some color splashes.
The mica powder was sprinked on top of the poured epoxy and locally stired into the epoxy. This is a neat way to add a splash of color here or there, but its probably not easy to stir around the filler (rough wooden blocks).
In reflection, it probably would have been easier to pour the epoxy into an empty casting mold, sprinkle some mica powder on the top of the epoxy, mix that in as desired, then insert he wooded pieces. Then, instead of taping down the wooden pieces, just use a flat block to hold it all down.
A piece of foam, like the 1" insulation sheets, could hold down the wooden chunks, prevent from floating out of the epoxy, yet it would be easy to remove, even if some epoxy ended up gluing the foam to the casting.
End of the First Video
At the end of the first video, the raw epoxy and wood chunk casting is shown just after it was taken from the casting bowl. Part two will show the remaining work.
Summary - Second Video
The second video is only half as long as the first, just 11 minutes. This video only shows the turning and finishing of of the cast wood/epoxy slug. THe bulk of the video is just turning the bowl. If that isn't the interesting part for you, watch the first minute, then skip to the 10 minute mark.
The final bowl was left fairly thick. The wooden chunks were relatively large, so its got big wooden spots and then large epoxy spots. The wooden center looks a bit out of place with the other rough pieces of wood, but its not noticeable from the side view.
Another interesting aspect is that the epoxy had some pearl colorant added. In some areas, it was fairly opaque and made the wood less visible. In other areas, the epoxy was mostly clear.
In reflection, if you are intending to create some turned works with epoxy, it might be worth it to experiment with different colors, different amounts of color, and also different filler materials as well as different filler material shapes.
It might even be worth mixing a few small batches of epoxy, coloring them with more or less of a colorant just to see how visible the filler materials will be and if you are getting a desired effect.
Overall, this was a great video and offered a chance to see some of the challenges of casting blocks that are going to be turned and also some insight into what its like turning a block that is composed of wood and epoxy.