This solution expands wool felt, and lubricates it with PTFE, intended mainly for resizing key bushings.
Shake well before use.
To avoid weakening the glue, do not soak key bushings with excessive amounts of fluid. A good way to apply Felt RX is by bending the end of a pipe cleaner 180 degrees to form a J-shaped loop. This will hold the right amount of fluid, and has the perfect thickness to apply the solution uniformly to key bushings without dripping.
We recommend using properly sized key bushing cauls to prevent over-expansion, which can result in the keys binding on the balance or front rail pins.
We do not recommend using this product on hammer felt. We will soon offer a voicing solution specifically designed for softening excessively hard hammers that do not respond well to needle voicing.