hi im trying to refurb my caliper but the two pistons seem seized have tried the airline to pop them out but it didnt work any ideas???

Squirt WD40 down the sides of the pistons. Use a strong G-clamp to push the pistons into the caliper body. Hopefully this will break the siezure. If this does not work apply more WD40 and some heat to the caliper body.
Try again with the compressed air and keep your fingers well out of the way of the pistons. A piece of wood in the gap where the pads would fit will dissipate the energy when a piston flies out.

Mal

Dont bother, with things like brakes you would be better to use yours as exchange items and get recons.

Its not much dearer than buying seals and pistons.

(1) With Cortina calipers if the piston is pushed in too far it appears to cut off the fluid inlet to the pistons.

(2) Never use high pressure compressed air --- highly dangerous .
Using hydraulic pressure is much safer -- but wear eye protection.
Also compressed air from a compressor is is 10 bar max -- brake pedal pressure can typically put 100 bar into the hydraulic system.

(3) If you use WD40 you will need to spend hours cleaning the caliper and piston with alcohol as WD40 although it contains some silicones it is mainly composed of gas oil and kerosene type hydro-carbons even the slightest trace left on a metal surface in contact with the brake fluid will eventually destroy all the rubber seals in the system.