clear bottom lap showing after hotcoat

hey im having an issue with the clear lap showing "cloudy" after hotcoat.  i will explain..

I laminate the bottom. come back next day and grind the laps. then laminate the top and hot coat.  after the board is done it shows where Where the lap was ground. it looks "cloudy" It only shows in certian light or different angles when looking at the board but it is very frusturating.  

Any suggesgion.  Smashing glass? Grinding too far?   so many variables but thought it was worth a shot... 

Also herd that styrene when dryed can cause glass to go cloudy?  

Thanks