There is nothing to bond at the back of bi-cast. It's just loose fibre that brakes away. The thick plastic skin is the only thing holding this stuff together, once that goes prepare for San Andreas!!
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You are right!
You also must know where these faults line run just like San Bernardino is predictable!
In like manner, as of bicast - it is the void of the veins and arteries that gives way to rip.
Besides leather as sub-patch, aluminum mesh in #1 and synthetic fibers in #2 is also used to match the Stress of usage.
An aqueous leather bond holds all these sub-patch materials just like fiberglass resin but difference is in the “flexibility”.
It is the 3 years warranty that instills confidence to our customers, more so to the Insurance Adjusters.
When they known that there is a warranty they are very relaxed with the idea.
So far we have no recalls.
#1 Aluminum Mesh

#2 Synthetic Fiber Mesh

Roger Koh
Leather Doctor®