Mint luster is from micro-flowlines created during coining. Using a "silver cream" will remove these leaving behind an obvious polishing. You cannot make mint luster, you can only destroy it!
You should use 100% acetone (e.g. Klean)... and 30 seconds of dip sounds like a long time, even if you were to dilute the solution. Besides, many folks like me look for some character in coins, and not just the toned kind.
I use Tarn-X on silver coins frequently with very good results. I dip the coins, mostly Morgan Silver dollars, for several minutes, then rinse in water. I dry them each with a soft cloth and afterwards use silver cream to gently apply a light coat which I then wipe gently leaving a mint luster. the so-called "collectors", the know-it-alls will say never clean silver coins in this manner. I have several hundreds of these Morgan silver dollars and they sell better than the non-cleaned coins. proves the 'collectors' are not only wrong but also dumb. Notice that the poster was a 1-message one. But nevertheless, sometimes Tarn-X may be appropriate if the coin is just scrap (i.e. silver coins in Poor condition). Also, it depends on the metal. In 1970, I used the cleaner on an uncirculated roll of 1968-s pennies I bought in 1968, and the pennies still look great. Will find a few and post them here....
Here are before/after photos of three of my bottom-drawer silver dollars that I cleaned with Tarn-X and a bit of soft-bristle toothbrush action. I would never clean a rare coin, but since I have these mainly for their silver content, the benefits of non-abrasive cleaning outweigh the negatives, in my humble opinion. I'll post some updates in a year and we can see what happens to the (unprotected) cleaned coins.