O.G./F.G. questions

[shlitzcan]

Whats the calculation equation to figure your abv from specific gravities?:rockin:

 

[GilSwillBasementBrews]

OG - FG x 131 = ABV

 

[Pappers_]

Hi Shlitzcan and welcome! I've moved your question from the Introductions forum to the Beginner's Brewing forum. Don't take that as any kind of admonition - its not, just keeping things in good order. You might want to spend some time looking through the forums, there are a lot of them!

Again, welcome!

 

[shlitzcan]

wow thats cool. ok another question. i just transferred a robust porter last night and my gravity reading is 1.020. the last time i brewed this beer i could only get it down to 1.018 and i had bottle bombs. i did a 7 day primary and a two week secondary and bottled for two weeks. for the first couple days the beer was awesome....then lots of head.....then blowing up in my cellar. how do i get that gravity closer to 1.010?

 

[J187]

wow thats cool. ok another question. i just transferred a robust porter last night and my gravity reading is 1.020. the last time i brewed this beer i could only get it down to 1.018 and i had bottle bombs. i did a 7 day primary and a two week secondary and bottled for two weeks. for the first couple days the beer was awesome....then lots of head.....then blowing up in my cellar. how do i get that gravity closer to 1.010?

Give us some details. What was your recipe, and what was your fermentation like - how did you control temps? What yeast? Did you rehydrate or make starter? How much did you pitch? When you bottled, did you batch prime? What sugar did you use? How much did you use? What volume of beer did you have?

 

[Pappers_]

The final gravity number isn't really the issue with bottle bombs. For example, I have a Wee Heavy (Strong Scotch Ale) that has a FG of 1.022 but it is completely done fermenting (I aged it for six months, I know its done). There is zero risk of bottle bombs with this beer, despite its high FG - the style calls for a high FG, by the way.

Two issues with bottle bombs: 1) is the fermentation complete? and 2) sanitation.

If your fermentation is complete, if the yeast are done working, you can bottle without fear of bottle bombs, regardless of the FG. For your Robust Porter, wait a couple of days and take another gravity reading. Then wait a couple of more days (if you're concerned) and take another reading. If the reading has stayed the same, then you know fermentation is done and it is safe to bottle.

An exception though is if you have wild yeast in the bottle - they can restart fermentation in your bottle and create bottle bombs. So be careful with your sanitation.

About your Robust Porter, often they will be a little drier than yours is now, around 1.012 - 1.015ish final gravity. But, if you are brewing with extract, often the final gravity will be a little higher than the standard range. There is no harm in letting it sit in the carboy/bucket for a few weeks, to let the yeast complete their work. In fact, the yeast will clean up after themselves, which is a good thing, if you give them a chance. In the future, there is no need to transfer to a secondary for this beer and many brewers would tell you that leaving it on the yeast is advantageous.

 

[shlitzcan]

ok grains

LB OZ °L PPG
33% 5 ~ Pale Malt (Maris Otter)
Mash 3° 37
33% 5 ~ American Two-row Pale
Mash 1° 37
10% 1 8 Victory Malt
Mash 25° 34
10% 1 8 Muntons Chocolate Malt
Mash 345° 28
7% 1 ~ Briess Special Roast
Mash 50° 34
3% ~ 8 Briess Caramel 120L
Mash 120° 34
3% ~ 8 Dingemans Cara 20
Mash 21° 37
0% ~ 1 Muntons Black Patent


fermentation was awesome. temps are in my cellar set at 69 deg.

i used white labs British ale (wlp005) I made a 500ml starter w light dme 2oz by weight.

 

[J187]

ok grains

LB OZ °L PPG
33% 5 ~ Pale Malt (Maris Otter)
Mash 3° 37
33% 5 ~ American Two-row Pale
Mash 1° 37
10% 1 8 Victory Malt
Mash 25° 34
10% 1 8 Muntons Chocolate Malt
Mash 345° 28
7% 1 ~ Briess Special Roast
Mash 50° 34
3% ~ 8 Briess Caramel 120L
Mash 120° 34
3% ~ 8 Dingemans Cara 20
Mash 21° 37
0% ~ 1 Muntons Black Patent


fermentation was awesome. temps are in my cellar set at 69 deg.

i used white labs British ale (wlp005) I made a 500ml starter w light dme 2oz by weight.

Cool. How about the priming the process? Batch prime? Amount of sugar, type of sugar, etc.

 

[shlitzcan]

3/4 cup corn sugar 2 cups of water. i just stir it until it all dissolves. i use this for a 5 gallon batch. which is all iv'e ever done.

 

[Pappers_]

This isn't about bottle bombs, but if you are consistently getting higher final gravities than you want, lower your mash temp (148F - 150F will typically give you a dry, light bodied beer).

About your bottle bombs, give it time and make sure the fermentation is complete, and make sure your bottles and caps are sanitized well.

 

[shlitzcan]

ok so this time i heated my mash tun up with a gallon of water at 160 deg. for a few moments before i started my mash. i started my mash with 165 deg water and after an hour the temp was at 153 deg. and i rinsed with 155 deg.

 

[WoodlandBrew]

Given that time line and gravity readings I would guess the bottle bombs were a result of contamination. How do you sanitize your bottles?

This is the easiest wy I have found:
http://woodlandbrew.blogspot.com/2012/10/not-just-sanitized-but-sterilized.html

 

[shlitzcan]

dishwasher, we have a newer one that is stainless steel that has a sanitize selection on it. i use that for new bottles. for re-used bottles i use star sans or iodophor and do the submerse in the sink and then set to dry.

 

[TheZymurgist]

If your fermentation is complete, if the yeast are done working, you can bottle without fear of bottle bombs, regardless of the FG. For your Robust Porter, wait a couple of days and take another gravity reading. Then wait a couple of more days (if you're concerned) and take another reading. If the reading has stayed the same, then you know fermentation is done and it is safe to bottle.

There is no harm in letting it sit in the carboy/bucket for a few weeks, to let the yeast complete their work. In fact, the yeast will clean up after themselves, which is a good thing, if you give them a chance. In the future, there is no need to transfer to a secondary for this beer and many brewers would tell you that leaving it on the yeast is advantageous.

^^THIS!

I've never understood where the idea comes from to transfer out of the primary after "X" number of days. If the beer is transferred before fermentation is complete, you're removing the yeast before it's done working. Even if the beer is transferred immediately after fermentation, the yeast isn't done cleaning up byproducts that are produced during fermentation.

 

[TheZymurgist]

dishwasher, we have a newer one that is stainless steel that has a sanitize selection on it. i use that for new bottles. for re-used bottles i use star sans or iodophor and do the submerse in the sink and then set to dry.

It's a good idea to use starsan or idophor on all of your bottles just to be safe. Actually, you ought to use it on everything that touches the wort after the boil.

 

[shlitzcan]

Thank you everyone for your replies. I just signed up to this forum less than two hours ago and have more information than i thought i would get in a week.

 

[TheZymurgist]

Thank you everyone for your replies. I just signed up to this forum less than two hours ago and have more information than i thought i would get in a week.

And welcome to the community! The knowledge I have gained here has been invaluable!

 

[WoodlandBrew]

The mash profile explains the 1.020 final gravity, but I'm still stumped on the bottle bombs. I used the dish washer method for years with no issues. The only time I have had gushers is from not mixing the priming sugar well.

 

[shlitzcan]

Hey guys i was wondering if you could look at my other thread i have about high abv and what im trying to do. thanks

 

[ajf]

OG - FG x 131 = ABV

The real formula is (OG - FG) x 131, otherwise you will end up with negative gravity.

-a.