Crystalization in secondary fermentation

[AdegaAguiar]

I racked each of my carboys containing Cab Sauv and Merlot, I noticed they each had what looked like sugar crystals on the sides of the carboys and stuck to the oak sticks i placed in the carboys. I don't think its anything funky but have never had this occur before. Any idea what this could be?

 

[stickman]

Potassium bitartrate crystals, it's a normal part of the process for wine from grapes.

 

[AdegaAguiar]

Potassium bitartrate crystals, it's a normal part of the process for wine from grapes.

Interesting... I've not added sulfites yet, but should I worry about filtering or anything like that when I do?

 

[cmason1957]

No need to worry about these, they are normal. The temps that your wine is seeing have dropped. Colder temps can't hold as much potassium bitartrate in suspension, so they drop out. Many of us will cause this to happen later in the process by putting our wines into a cold environment. Many in America consider this a flaw (it isn't), in France, from what I understand it is considered a sign of high quality grapes. You can't filter this out. Once they form and drop out, they will not go back into suspension.

 

[NorCal]

We had a “cold” snap a week ago where the low hit 38-42 for the week, I rolled my Chenin Blanc out of my wine box for the sole purpose of creating these tartrate crystals. Better now, than in the bottle later.

 

[AdegaAguiar]

Very true. Should I go ahead and add the sulfites now then?

 

[Machinist Nick]

As long as your specific gravity indicates the fermentation has finished. Somewhere in the ballpark of .990 and consistent, stable readings over a few days. Sulphites and "wine diamonds" (tartarate crystals) don't really impact each other.

 

[jburtner]

Also known as "Cream Of Tartar"
https://en.wikipedia.org/wiki/Potassium_bitartrate
Cheers!
-johann

 

[mainshipfred]

Off the wall topic but Cream of Tartar when fully saturated has a pH of 3.56+/- .05. I always keep a bottle on hand as third point when calibrating my pH meter.

 

[jburtner]

I used that method recently to confirm my meter cal

Found a procedure here:
https://vinmetrica.com/wp-content/uploads/2017/October2017NewsletterAttachment.pdf

5. Cream of Tartar test: measure the pH of a saturated solution of cream of tartar which has a pH of 3.55 at 25 °C. a) Get pure cream of tartar powder (grocery store stuff is fine, provided it’s pure and not too old), or reagent grade potassium hydrogen tartrate, also known as potassium acid tartrate or potassium bitartrate. Call it KHT for short. b) Place about 1/4 teaspoon of KHT in 20 mL of distilled water. Mix well for about 30 seconds. You want to be sure the solution is saturated, i.e., everything that can dissolve, has dissolved. There should be some undissolved solid left. c) Decant or filter the solution off the solids. d) This solution has a standard pH of 3.55 at 25 degrees C (78 °F). The calibrated pH electrode should measure within 0.05 pH of this value at temperatures from 20 to 30 °C. Discard the solution after 24 hours.

Cheers!
-johann