I'm not sure because I haven't used menthol crystal. If you use it according to the 500ml standard, you can easily check the results. I think it would be effective to increase the amount of JWA and add caustic soda and fine clay powder. Please refer to the following:
- https://www.youtube.com/watch?v=kbO-x9dyZ_Y&t=116s
- https://www.youtube.com/watch?v=r1gs8efDlgY&t=28s
