Ok so my refractometer broke like two months ago and since then what I've done is once I get my pre boil volume I'll mix real well and pull a sample then stick it in the freeZer to chill it to 70-75 deg then I'll pour that into my test tube and test it with a hydrometer. Same thing today and I was four points high on my pbg however after boiling an hour and hitting my volume it seemed or looked like i was two points low on my og but I find this hard to believe since logic would say if your above your projected pbg and you boil off the correct amount I should be higher than my projected og right? So I wondered if temp in the pbg has my reading off or maybe I mean my og sample was a little foamy and if anything I prob hit my projected og of 1.064 which is fine but shouldn't it be higher if again my pbg is measured higher and I boiled off to my correct amount? Just curious if I'm missing something and yes my hydrometer has been checked multiple times in distilled water and its spot on but maybe I'll check it again I've done the same with the last five beers I've made and all have hit projected og on the hydrometer.