I agree. We can now see the direct negative impact on the health of this forum. One can only speculate why the powers that be on this forum tolerate this. Gloomy thoughts.
To get back on topic…
In my experience, I do see differences in wort darkening based on boil intensity. I’m using a direct fire system, and at hombrew scale the kettle bottom in contact with the wort has a very high surface to volume ratio.
That’s a very literal read of that quote applied to this situation Jim.
Folks, this has to stop. This has gone from a forum where everyone comes in to share brewing knowledge and experience to a place were 1 out of every 10 posts is hijacked and subjectively over ruled based on 1 or 2 people’s text book readings. No one’s experience matters any longer. You can have a gold medal winning beer at the World Beer Cup but is will be flawed because 1 or 2 folks on this forum has determined that, based on what they have read, you didn’t brew it right. It is utterly ridiculous.
If your gig is LODO brewing, that is great! Keep doing it and keep preaching it brother’s and sisters! But stop coming onto this forum and telling everyone else is f’ing doing it wrong. Disagree, but stop doing it by screaming “WRONG” and then discrediting based on some arcane science that no one but you has uncovered in some brewing science book no one has read. If you have such knowledge, please bring it out and discuss it. But acting as if YOU personally are the sole arbiter of brewing knowledge will not be tolerated any longer. Period. And YOU know who I am talking about.
This is a forum for ALL levels of brewing. From the very first pitch of yeast to understanding water chemistry to complex microbiology. What has happened is this: A new person posts a question. Answers are given. Then one or two people come in with some seriously challenging and arcane (and frankly, ancient) challenges to simple answers to simple questions that, in the end, make this brewing thing seem so much freaking harder that it really is. And, while I really am digging the science aspect, it is UNWELCOMING. Brewing homebrewed beer can be as simple or complex as you want to make it. There are people making good beer with store bought extract and the yeast under the lid. Period. There are people making all grain beers out of 2000 dollar machines that is CRAP. Period. It doesn’t freaking matter if you disagree with their methods of brewing or not. If the beer is good it is GOOD. If it isn’t, find a nice damn way of telling them.
The goal of this forum is for people to come here to learn how to brew great beer. It is why I am a moderator here. It is why I contribute here. It isn’t something I have to do. It is something I want to do. I want to see this forum succeed. I want to welcome new people here. I freaking want CHALLENGES! The more science the better! In spite of the fact that I am a brewmaster at a brewery distributed state wide, I am seriously challenged when it comes to much of the brewing science discussed here. I don’t understand much of it, yet manage to churn out award winning beers anyway.
Like all crafts, what makes this fascination great is that no matter what your skill level and no matter what your brewing knowledge, there is always room for improvement and learning. I love it! But we also have to keep room for the new folks coming it. And this constant bickering is ridiculous.
I personally won’t tolerate it any more. I have been a mod here since this forum started. I am also fine being removed from that post if necessary. There are hard and fast rules about being a member here. And, while no rules have been broken necessarily, I am moved to action by my personal belief that we are starting to have serious divisive disagreements that are not only detrimental to the forum society, but are also becoming extremely unwelcome to the newcomer.
Seriously, it stops now. Sharing knowledge is completely encouraged. Being a Nazi is not.
I would say that boil temps ultimately matter in regards to what temperature is takes to get a slight simmer going. That temperature is different for people living in different elevations and one should aim for whatever temperature allows for a boil vigor on the order of a slight simmer.
I guess the caveat being if the style calls for large amounts of evaporation (Scottish), etc. I don’t personally brew any styles that would require an intense boil-off but some may do that.
To me boil temp matters for consistently hitting OG which contributes to fg. I brewed my first batch at my new house and due to environmental variables boiled too hard and had 4 gallons 1.062 OG pale ale instead of 5 gallons 1.052 APA.
Most texts suggest a 5-6% evaporation rate, and the right isomerization of hop resins, oils, and polyphenols. Which a vigorous boil you get more break material and provides the appropriate amount of protein, MgSO4-N, and FAN/L. Then there is thermal stress on the wort drives off negative flavors. ~Kunze 3.4
After kicking this around a bit I think I will try a less vigorous boil on my next brew day. My current way is not ridiculously vigorous to begin with, but it’s not terribly hard to simply look in the BK and turn the knob down a little. Plus I just switched from 10lb propane tanks to 30lb, so I might need to anyway. I always estimate 10% boil off, but I find it varies a little depending on humidity, temperature, wind etc. I’m not very anal about precisely hitting gravity targets either, within 5pts doesn’t really bug me. So I’ll try boiling just above a simmer next time.
I’m also going to try no sparge next brew day. One batch normal procedure, one no sparge. Maybe I’ll let the normal one rip on the boil, and throttle back the no sparge one.
That’s the right section but not sure about your interpretation. Chapter 3 is a gem.
Actually, Kunze states…
"By reducing the length of boiling, boiling more gently at a lower temperature and formingfewer shear forces, more coagulable nitrogen remains in the wort giving rise to the expectationof better foam retention. 20-40 mgcoagulable nitrogen/litre cold wort is desirable. At the same time, the formation of ageing relevant
substances is reduced.
And
Only a few decades ago a high rate of evaporation was therefore a criterion for the quality of a wort kettle, and a kettle with a rate of evaporation of 10-15 % of the wort content was considered to be a high performance kettle. In the meantime this has changed, as will
be shown. Today a rate of evaporation of 4 % is aimed for with good evaporation efficiency."
There is more as well. Not trying to pick a fight, just showing what I have found.
Here is a “side by side” of worts with regards to boiling.
I’m not sure if the pre and post boil color comparison is truly valid since there is a significant increase of wort solids and sugars. That would increase color by itself. But I do agree that the heating intensity should increase the darkening. We just need a better test and result in order to make the comparison.
5 to 6% is teeny compared to typical homebrewing results. I’ve heard that keeping it below 8% is recommended on pro systems. We are probably 2 or 3 times that. The common lore to keep the kettle uncovered is a big reason why our loss rates are too high. I keep my lid about 2/3 on and I still have too much loss. My wort is only slightly rolling, so it looks like I need to cover up a little more.
I’ve learned new stuff in this thread!
Bryan, are you still using a covered pot during the boil (i.e. the video on your facebook shows a lid that has a pie-shaped sliding piece that you can view into the boiling wort)? And, if so, do you keep the wort covered for the entire boil? I’m wondering about the potential for that to lead to DMS/SMM retention in the wort. I ask because for a couple batches last year I attempted a similar, covered-boil and the results were not great (not terrible, but certainly not an improvement from my process at the time). I’ve quickly moved back to open pot with reduced vigor, generally exceeding 10% evap by a small amount, and have liked the results pretty well. I’m looking to revisit a lower-evap, lower-vigor, lower-stress boil but would want to avoid the “not great” results of last year. Cheers!
Edit: I should mention that the “not great” results from last years couple batches very much seemed DMS-related. My impression what a slight cooked vegetable character. I’m not sure other folks picked up on it, but I certainly noticed it. It’s entirely possible that I misdiagnosed my beers and it was just a recipe formation issue on my part.
I do still use the lid. I do still boil completely under the lid. I get about 6-7% boiloff. I do remove the lid for the chilling whirlpool, and don’t replace it under the wort is under 100F. DMS is a concern. I have found I can pick it up in the wort very easily and its about gone with 10-15 minutes left in the boil ( 60 minutes). If you don’t pick it up in boil, I would bet its coming from the chilling/whirlpool portion. 10% and below is something I shoot for.
I see about 1srm color pick up from boil. If I boil any harder than that, I notice immediate flavor degradation. That flavor for me that I get right away is what I call a boil hop flavor… Kinda vegetally, kind of smokey, like scorched hops, its not in your face, but I can pick it up. Just be careful about too soft of a boil, I had many a batches with DMS until I got it dialed in. I would call 8% the sweet spot for us.
Thanks for your response, coupled with the reply to martin, I’ll aim for an 8% evap rate on my next batch and see how it goes. One more question, if you don’t mind: The lid you’re using doesn’t vent the steam somehow does it? (like having a vent/vacuum port on the lid that’s sucking out steam throughout the entire boil)
No it does not, and I see where you are going. 
I did not notice any issues with “drip back” or condensation, but again YMMV, FWIW, IMO, ETC. 8)
I had the same thought about concentration. Glad to see I’m not a dolt.
I guess I’ve been lucky with stove top brewing in that it’s pretty hard to make the boil jump with a typical burner. I still get more then 10% boil-off, though, even with a partially covered pot.
When I’m brewing outdoors, it’s much harder to manage the boil. Or, more accurately, it takes more monitoring and adjustment.
Thanks again for sharing. I just wanted to make sure that a plain and simple pot lid wasn’t an oversight only to find out later that you in fact vented the steam generated during the boil. I (somewhat reluctantly) look forward to taking another stab at a mostly covered boil. Now I have some recipe and process modifications to make with the new reduced evap rate I’ll be shooting for.
I was off the forum for about a week and was wondering what had happened in the other threads, but now I see. Glad this thread is back on topic. I have gone to a gentler boil with the lid on 3/4 or more, but not from anything stated in this thread - I just wanted more wort, so I end up with more beer to fill the cornies up fully when it is done. My boil off rate had been just too high (like 12 -15%). So occasionally one stumbles onto a process that helps in more than one way…by the way, I do occasionally remove the lid during the boil to let off some steam and drip off some condensate (DMS worries plague me regardless - old habit…) and I leave the lid off of the kettle during the chill down as my brew guru said failing to do that is almost a sure way for DMS to form in the few minutes of chilling. Could be true and I don’t want to risk a batch to find that one out.