static on blast cabinet

[RBDIVE]

Ive startted getting what feels like small electric shocks when using my home made blast cabinet, never happend before, its not all the time and sometimes in the left hand or the right(gun-hand) never both. any ideas? do i need to ground myself or the cabinet?
specs are
15mm MDF cabinet with double top loading doors one with persepx window
Using M-mart oxide powder 60grit of 14cfm comp

 

[madkayaker]

ground the cabinate and the work peice

 

[rtbcomp]

And the gun. Proper blast hose has a substance added to the rubber to make it slightly conductive to dissipate static.

I've seen sparks 1/2 inch long whilst blasting.