I've worked at getting this to work, and these are my findings:
- Not all salts are created equal. The guy in the video doesn't specify what type of salt he uses, but i did some further research on the "old golf trick" he claims to be using and the salt required is epsom salt. Why does this matter? Because Epsom Salt is only salt in name and appearance. Epsom Salt is actually Magnesium Sulfate which when mixed with the water increases it's density by .2 grams per cubic centimeter, this making the water more dense than most other dice.
- the quantity of salt is everything. Using a lot of water and not a whole lot of salt like it appears to be the case in the video will do nothing. your dice will sink and that will be the end of that.
- Opaque dice and solid dice make no difference on the balance of the die, it's simply the way the die was made. What i did find is dice that are multi-colored speckle like the one below are too heavy to float in the salt water solution, everything else is fine and equally likely to be balanced.
- Get a small cup, i used a two ounce Styrofoam courtesy cup from a local fast food restaurant, and fill it about 3/4ths the way full with Epsom Salts.
- Add "faucet hot" water to the cup slowly until it's basically full should be about an inch gap between the top of the Epsom Salts pile and the top of the water.
- let sit for a minute or two.
Once it's done curing so to speak you can add your dice, 1 at a time, to the solution wait until the die has stopped rotating and found it's favorite side so to speak. From there just gently roll the die in the water so it spins freely for a little while, wait till it settles again. record the number it lands on. After about a half dozen spins you'll see a trend. either it lands on the same side repeatedly, lands on sides close or adjacent to each other or has no consistency at all.
If the die repeatedly lands on one or two sides that are close to each other, it is weighted to those sides. if it lands on five or so adjacent sides it's weighted the corner that intersects all of the faces. If it has no consistency what-so-ever, then the die is balanced.
To take it further, the slower a die turns to the weighted side, the more towards the center the weighting is. The faster a die turns to the weighted side, the closer to the surface of the die, the weight is.
Let us know in the comments what your experiences with this method are. We found that almost all of our D20's were biased for better or for worse. out of the entire group of five people, with a GM having almost a dozen D20's, there were only 5 that were perfectly unbiased.