Hammer Head

Hi there all! I recently ran into an issue where I’m get large voids within my casting. I’ve been using RC3 casting resin with a 5 % mbs added with great results. I ran out of alumilite mbs twards the end of my pouring session and switch over to Fasco mbs and immediately noticed the voids or larger air pockets. Can anyone recommend an explanation as to why or what could have caused this. It just seems suspect being that happened right at the change of product! Appreciate any insight. Thank you.