Would also recommend...
Consider lightly scouring the surface of the grips with a #0000 steel wool pad when you pull them from the solvent soak.
When/if you choose to apply a Tung Oil Finish, consider sanding the Tung Oil in with 220 grit sand paper, or perhaps scouring it in with #0000 steel wool. Liberally apply the oil and while it is still wet, gently sand with the grain. Let the oil set for a minimum of 5 minutes, until slightly tacky - wipe off with a lint free cloth.
If you choose to apply additional coats of Tung Oil, sand the finish in with higher grits (400/600 etc.). Please wait at least 24 hours between coats, especially when using Tung Oil Finish, which is not pure and cut with solvents. This allows the solvents in the finish due time to evaporate. This is especially important: If any solvent is trapped in between coats, it will visibly start to break the wood down in time.
If you notice that you have not removed any wood when sanding or wiping the grips down, and are not satisfied with the final outcome - consider dry sanding them with an appropriate grit to reach wood. Then, apply Tung Oil mixed at a Ratio of 5 parts solvent (mineral spirits will do) to 1 part Tung Oil. Thinning will allow you to reach wood when you sand the finish in - otherwise you will again be gliding on dried Tung Oil.
I hope to be of some help to you!
-Will
