Thick mash

[himesrun]

I mashed in some peach 10 days ago. It was a bit on the thick side if course when I measured the starting SG. It's now dropped below 1.0 and still bubbling like a nut...EC1118. Will a thick mash cause a false reading higher or lower than actual?

[himesrun]

FYI, starting SG was 1.080.... actual 1.085 after the temperature conversion...

[still_stirrin]

...Will a thick mash cause a false reading higher or lower than actual?

Well, yes,

Alcohol has a lighter density than water. When measuring the "specific gravity" with a hydrometer, you're actually "comparing" the density of the liquid to water. When you start your must ferment, the sugars present increase the density and your SG is greater than 1.000. But as the ferment progresses and the sugar is turned into alcohol, the density will reduce closer to water. Remember, your ferment is not not just water, but also includes alcohol (which has a lighter density). So, the measured specific gravity can actually fall below 1.000.

Starting with a higher original gravity (OG), like your case of 1.085 temperature corrected, this "alcohol depression" can be augmented/accentuated. There will always be a little error when measuring the final gravity (FG) due to the alcohol present. But, the real judge of whether or not the ferment is "terminal" or done, is when the yeast flocculate (stick together) and settle. And the fermentation near the end is asymptotic as less and less sugar molecules are available to the yeast to convert. Activity reduces slowly near the end of the process.

Your question regarding the pulp in the fruit must, whether or not it affects the gravity reading. Well, the viscosity which is the "stickiness of the molecules" can affect the reading. But it doesn't necessarily relate to a density change. Temperature can affect the density readings too and can affect the viscosity as well.

It is always best to try to measure the specific gravity of a liquid solution without pulp or floating solids in it. The solids can affect the ability of the hydrometer to properly "float" in the liquid. And it can make reading the visible meniscus difficult too.

I hope this answer makes sense to you and doesn't further confuse you. The quick answer is that the hydrometer will give you a "relative idea" of the progress of the yeast's ability to convert the sugars to alcohol.
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[himesrun]

Yup, makes perfect sense. This is my first time with fruit. I'll let her run a couple more days just to safe....thanjs!