Hello,
what are the ways to extend the pot life of polyester resin (if possible)?

The trouble with inhibitors is not all polyesters/vinyl esters react equally. I can actually get TBC inhibitor locally, but the polyester resin I get from the same supplier does not respond well to it. It has virtually zero effect on the pot-life, but has a massive effect on how fast the resin kicks once it has begun to gel. 

On the other hand, it works well with the vinyl I get from that supplier.