\Rhino_66 said:You can buy bleach from chemical supply companies, but be careful. Typical reagent grade bleach is 12% to 15% hypochlorite. Clorox and other home use brands are around 2% to 3% hypochlorite. The reagent grade will really damage almost any material that it comes in contact with. It will destroy nylon and other plastics even with short exposure. The reagent grade stuff will remove the stain, but will damage the stock beyond repair in a very short time. Stick with the concentrations like the home-use brands. You can thicken bleach by adding a little corn starch to make a paste. Think of it as bleach gravy.
You could also try the dishwasher trick afterwards to get all the bleach out.