Partial Mash and Refractometer

Hey guys,

I just brewed the URCA Vanilla Porter tuesday and had a few questions.

I mashed in a gallon and a half of water on a gas stove and in a bag then sparged through the bag and a strainer with 1 gallon of water at 170 degrees. It wasn’t easy to get a stable reading of the temp through the mash as the thermometer would catch on the bag when i moved it around so I hope I mashed long enough at the right temp. I just wondered if any of you had this happen as well and what can I do to get a more accurate reading?

The other question deals with the refractometer. I believe I had it calibrated correctly and the beer measured only a 1.047 when the recipe said it should have been approximately 1.061. That’s a pretty big difference I think. I was thinking I may not have mashed long enough but I really don’t know why the OG is so low.

Any advice would be much appreciated!

Was the wort room-temp when you measured it with the refractometer?

It was a probably closer to 80 degrees so no it was not. The unit I have is an ATC unit so I was at the understanding I didn’t need to do any substitutions. That and I couldn’t find a temp table.

You are not giving us enough info to give a reasonable answer.

How much grain was used. What is the recipe volume and what volume did you end with.

I use an ATC unit. I spoon wort out of the boil kettle onto the prism to take a reading.

[quote=“Nighthawk”]I use an ATC unit. I spoon wort out of the boil kettle onto the prism to take a reading.[/quote]I also have an ATC unit, but I found that unless I submerged the prism and cover in the mashtun or the boiling wort to preheat it that I did not get an accurate reading. Started chilling the wort with an ice-cold bowl for both the refracto and pH readings and found it to be much more consistent.

But to the OP, 80F isn’t going to throw it off. As Nighthawk said, a little more info on the recipe and volumes would help to figure it out.

I mashed with about 4.5 pounds of grain at approx. 156 degrees for an hour in 1.5 gallons of water. I also added 3 pounds of gold malt extract and 2 pounds of dme 45 min into the boil along with a teaspoon of irish moss. I took the reading after I put the wort into the carboy using a small sample with the beer thief.

The only thing I added to the recipe is the irish moss. otherwise it was all according to the recipe

Was it 4.5lb, or 4.25, or 4.75lbs? Did you sparge? If so how much water was used.

What is the ending volume after the boil.

I used 4.75 pounds of grain in 1.5 gallons for a mash, and I sparged with one gallon. The boil volume was about three gallons and after the boil it was 2.5 gallons. I added 2.5 gallons to the carboy. I put 2 gallons in the carboy that had been in the fridge. Then dumped the wort in followed by another half gallon of water. I rocked the carboy for a couple of minutes to aerate then took my measurement. Also I have noticed no signs of fermentation now and it’s been 3 days. The sediment has piled up in the bottom of the carboy but no bubbles or foam. Pretty rough first partial mash…

Your expected OG is based on an efficiency of ~75%. That might be a little high. But that only accounts for a couple of points.

Most likely, even though you shook the carboy to aerate, the wort and water didn’t get mixed completely. Don’t worry, the yeast will find the sugars.

What yeast did you use?

I believe you should see fermentation by morning. You could add another pack of dry yeast, but I don’t think will be

When the beer is finished fermenting, you can take a hydrometer and refractometer reading and calculate the OG.

I used the 1056 American ale.

I wasn’t home over the weekend, but when I got home Sunday afternoon fermentation had begun and I’d guess it was a day in. I just needed to be more patient I guess. As for the readings I won’t worry about that until I test for FG.

There is much much more activity and sediment in this fermentation. Is this to be expected with irish moss?