Suggestion for armor items

I came up with an idea of "how to improve armor without highly altering suvivability" (in the meaning of not becoming/being invulnerable). And also, making it cost and promote crafting.

White drop + granite flask:

Chance to alter base white armor points by expending a granite flask on them.

Requirements:
1. item must achieve 20% quality for this "added value roll" to be performed on it.
2. can only be performed by players from to/above lvl 27.

Value variation:
Value rolls from 30 to 150 for lvl 27-50. (it can be arguably changed)
Value rolls from 60 to 300 for lvl 50-70. (it can be arguably changed)
Value rolls from 90 to 600 for lvl 70-90. (it can be arguably changed)
Value rolls from 120 to 900 for lvl 90+. (it can be arguably changed)

Downside:
0. Cannot be performed on other items besides white ones (rule zero/default rule).
1. Item loses ability to alter quality. Cannot be capped at 20% quality anymore. Not even have quality.
2. Can only be performed once per white item. That's the risk, you may waste a granite and the white item drop itself.

An example would be:

White item has 275 base armor pts:

Player capps the white item to its 20%, and rolls a granite flask on it: (i.e. 30-150).
Item achieves a plus +100, making it: 375. Numbers on item shine yellow/grey due to crafting.
Player has a new item with a better number base. Can now roll affixes and improve item.
Granite flasks market value increases.

Feedback of the idea will be highly appreciated.