Tom,
Kraton is a synthetic rubber made by GLS. It may be licensed to other companies but at KA-BAR, we stay with GLS. It is pretty resistant to chemicals but it will start to de-grade over time if used continually. In addition to chemicals; heat, abrasion and UV radiation also contributes to this. Inspite of this, Kraton is a very good material. Here are some tips:
1) Keep it away from heat sources...camp fires, car windows in southern states, ovens, 300 Deg F + and you should start to worry....you get the picture.
2) Don't stir chemicals with your knife handle..gasoline, DEET, stove fuel....you get the picture.
3) Be careful how you use the Kraton. It will wear and abrade. We use Kraton G (the most resistent of the Kraton Grades.) We also keep the Durometer hardness fairly high: 87-92. IIRC.
4) Make sure the handle is, indeed, Kraton.You would be surprised how many advertised handles are not really Kraton.
I have found that if you keep the Kraton handled knife in a normal storage place, you will be okay. Just check it occasionally. Knives and knife materials like to be fondled and wiped down often....It's a fact...look it up.
Hope this helps.
Best Regards,
Paul Tsujimoto
Sr Eng
Prod Dev and Qual
KA-BAR Knives