Yes, you can calculate their combined cal/cm2 protection. E.g. base layer of 5 cal/cm2 and outer garment of 9 cal/cm2 = 14 cal/cm2.

No, untreated cotton garments have a low ignition temperature. (It can reach temperatures of up to +1000 degrees against the body.)

No, but flame-retardant garments tested in accordance with the IEC61482-2 arc standard are the foundation of arc-protected garments.

• Flame-retardant cotton garments contain chemicals, Proban being the most commonly used.
• Inherent flame retardant fabrics do not contain chemicals. The protective properties are woven into the textile fiber to ensure lifelong flame protection.

No, the materials have been developed and flame-retardant clothing has the same high comfort and feel as other workwear, e.g. flame-retardant clothing in stretch material.