evaporation rate

Could this be calculated by comparing pre and post boil gravities? Just a thought I had today while reading another post about efficiency calculations.

I know its much easier to simply measure quantity, but I have found variations in different vessels and their graduations.

Is there a formula out there to do this?

I would thinkit could be an accurate way to measure volume.

The problem with using only the gravities is the rate of evaporation depends on the geometry of the vessel, ambient conditions, heat applied to vessel.

If you know at least the starting volume and use the same vessel and can apply the same heat and brew in similar weather conditions, you could make a formula that would tell you what your ending volume would be based on the length of boil, but it wouldn't be any different than what most brewing software provides.

After a couple of batches you will get an idea of how much wort you end up with after a certain length boil. I personally don't try to make it too precise, usually adjusting volumes by 1/4 gallon increments, and even that is pretty anal I bet compared to others.

baldilocks said:

After a couple of batches you will get an idea of how much wort you end up with after a certain length boil.

Click to expand...

This!

I think it can really only be gauged corretly through experience. Take VERY good notes on the next few batches. Be precise with your water levels and exactly what temp you are boiling at. I built up to 90 minute boils by messing with my temp and lengths of boil (started with a high setting and 60 minutes on a stove top...now I can get a good boil at 8 through 90 with predictable results.)

Always aim low...you can add a cup of water at the end, but I really hate throwing out any hoppy-wort goodness.