After being advised by a builders merchant that Blue Grit was a cheap and brilliant substance to apply to my ceilings before plastering, I jumped at the idea and bought a tub. The ceilings were coated 48 hrs ago and this morning I began plastering.......room1 the fuc*ing ceiling bubbled..then fell. There was no bond at all for the plaster......so I scraped the blue sh*t off.......is this a regular issue with blue grit???