The small bridges simply do not allow enough glue surface for the increased tension of medium gauge strings.
All of our acoustic guitar necks can be adjusted with a 5/32" ball-end allen wrench.
The overwhelming majority of cracks (and lifting bridges) are caused by inadequate humidity.
Exposing your instrument to a low humidity environment can cause the woods to contract and change shape, which can lead to cracking and a host of other problems.
If you are considering placing a custom order, your dealer will be able to provide you with a price quote and time frame for delivery.
Any high grade, commercially available polish should be fine.
We use D'Addario phosphor bronze strings and have for many years.
For small bodied guitars (Baby, OM*, 0, 00, 000, C10), we use: J16s - light gauge (.012, .016, .024, .032, .042, .053).In order to keep your instrument in proper playing condition and prevent cracking or other structural problems, it is very important that you maintain a similar level of humidity where you store your instrument.In many climates, it can be difficult to achieve an adequate humidity level without help from a soundhole humidifier.You should have some room to lower the action from these measurements, but keep in mind that an ultra-low action usually requires lighter playing or adjusted technique to prevent buzzing.Feel free to give us a call if we can be of any help.For large bodied guitars (D, CJ, DS, SJ, Archtop), we use J17s - medium gauge (.013, .017, .026, .035, .045, .056). Due to the footprint of the "belly" bridge, there should be plenty of glue surface.