Large Variance between Estimated OG and Actual OG

Brewing Processes
1

I brewed an over the top brown ale and input my ingredients into Beersmith.  IT gave me an estimated OG of 1.070 but when I took my reading when it had cooled down to 68 degrees it was 1.083.  What would cause such a large variance?

Here is the ingredient list:
.75 lb Chocolate Malt Grains
.5 LB Caramel Crystal Malt Grains
.06 LB Roasted Barley Grains
1 lb Amber DME
1 lb Light DME
4 lb Unhopped Light LME
3.3 lbs Hopped Light LME
1 lb Dark Brown Sugar
.75 lb CLover Honey
1 oz Nugget Hop Pellets
2 oz Williamette Hop Pellets
1 oz Fuggles Hop Pellets

Any input would be great.  Thanks!

2

Was it a partial boil?

3

It could be stratification if it’s not well mixed, I think that’s what Sean is getting at.  It could also be that you don’t have 5 gallons of finished wort, if you have less you would expect it to be higher gravity.  You’re probably not off enough to cover that spread, but it could explain part of it.

4

Not exactly sure what you mean…  It was a concentrated boil of 2 gallons then added water to make it 5.5 gallons.

5

Tom means that when you added your water, it was throughly mixed.

The part you took your sample from was a little more of your 2 gallons of wort and less of your 3.5 gallons of water so it appears stronger.

6

So before I pitch my yeast I should probably take a least one more gravity reading after a good aeration, correct?  Right now I have a starter going and waiting until full Krausen before pitching

7

In my experience you still won’t be able to get consistent readings. The only way to be accurate is to take the reading from the wort before topping off, then divide by the dilution ratio.

Also, I get an estimated OG of ~1.077, so you may not have been as far off as you think. That’s assuming 43 point-gal/lb for the DME, 36 for the LME, 45 for the brown sugar, and 38 for the honey.

8

I wouldn’t even bother with a reading.  Just calculate the OG.

9

Yeah, all of the extract/honey/sugar will be at 100% efficiency, so minor efficiency changes with the steeped grains aren’t going to make a huge difference in the OG.