# Who Does An Iodine Test?



## SJW (29/6/07)

How many of us out there do an iodine test prior to mashout or sparging? 
And how do u do it? 
I just put a drop of mash liquid on a white plate and drop some iodophor on it. But what I have noticed that even though the iodine test may show conversion is complete after 15 or 20mins with some of the Joe White pale malts or a grain bill with low adjuncts is there any advantage in letting the mash go for the full 60 or 90 mins after this? And if u was to finish the mash after 15 or 20mins, and a negative iodine test, would this be when a mashout would be necessary?
And while I'm on the subject, if your mashing at 3:1 do u think there is still a need to mashout?

Steve


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## therook (29/6/07)

I have done only 5 AG's and never tested yet....

You should make this a Poll Steve.

Rook


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## DJR (29/6/07)

I did a few times then stopped. Recently i've done it with my 35 min mashes just to make sure - the 35 min mash batches i've done have shown full conversion, got 88% efficiency and have had no problems attenuating  Bit of a time saver really. Wouldn't do it for all beer types though, but it seems to work.


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## Velophile (29/6/07)

I've done one or two tests. Just to prove to myself that there was something going on in the tun while the lid was on 

I used Betadine instead of Iodophor & also tested the starch-goes-black thing by adding a pinch of corn flour to the test plate. Very kitchen chemistry!


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## Online Brewing Supplies (29/6/07)

I do it on all beers except those darker than Iodine solution.Better to be sure.Dont want to end up with a BLUE brew as its known.Most pros I know ,well the good ones still do it.

Gryphon Brewing


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## alexbrand (29/6/07)

Me!

I do these tests if I don't forget them......  
I think if you run a (well) know mash programme there is no need to do it. Sometime ago I had two Blausude (blue brews) and I could not find any bad taste or flavour in the beer. So IMHO I don't need it anymore...

Alex


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## Kai (29/6/07)

Never done it, unlikely to ever bother. Remember an iodine test shows the presence or absence of starch, not the absence or presence of fermentable sugar. There is a glorious no-man's land between the two during the mashing process. I don't see the need to do it at home unless you're back-checking the cause of a stuck ferment or using really skanky malt.


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## Chris (29/6/07)

I used to do it quite often when I started mashing, and now do it ocasionally, if I've used a lot of adjuncts. Now my mashes are now more based on empirical observations.


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## Online Brewing Supplies (29/6/07)

Kai said:


> Never done it, unlikely to ever bother. Remember an iodine test shows the presence or absence of starch, not the absence or presence of fermentable sugar. There is a glorious no-man's land between the two during the mashing process. I don't see the need to do it at home unless you're back-checking the cause of a stuck ferment or using really skanky malt.


So really you have answered the question on why you should do it. B)


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## Kai (29/6/07)

Why you should do it when you have trouble, yeah. Otherwise, I figure RDWHAHB


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## Online Brewing Supplies (29/6/07)

Kai said:


> Why you should do it when you have trouble, yeah. Otherwise, I figure RDWHAHB


 I dont follow your thoughts.What is RDWHAHB got to do with it.Not very scientific.Each to there own.I do it because I want to reproduce good beer and cut down the variables.Not saying you dont produce good beer :super: but its the way to remove F ...ups.Every time you get new malt it is different in it parameters so a it was good last time approach is not good.All breweries do regular testing on all variables water, malt, hops and just about any thing you can think of.How would you feel if I sold you skanky malt? These tests are for good reason. B)


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## Thirsty Boy (29/6/07)

I do one if I have done something unusual where I think conversion might be effected.

Lots of adjunct, larger than usual sourmash, dodgey or new/unusual malt...

But like Kai said, its not much good other than an indicator of when things have gone wrong.

iodine goes black = bad
iodine doesn't go black... not necessarily all hunky dorey

Or thats what I reckon anyway

Thirsty


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## Mr Bond (29/6/07)

I'm with Kai!

Never done it,Can't see myself doin it.Nearly 30 AG's under the belt without using it so its prolly a little late to start anyways.My taste buds tell me if its converted or not.sweetest preboil worts are always the wheaties(yum).

*hey Kai* your a mod .Could you possibly change this to a poll so we can see some %ages?

*Q 1. Yes i do

Q2. No I don't

Q3. I used to ,but not anymore.*

Just a thought /suggestion.

Dave


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## Stuster (29/6/07)

Mr Bond said:


> I'm with Kai!
> 
> Never done it,Can't see myself doin it.Nearly 30 AG's under the belt without using it so its prolly a little late to start anyways.My taste buds tell me if its converted or not.sweetest preboil worts are always the wheaties(yum).
> 
> ...



Maybe with another option of "sometimes/occasionally", which is me. I'll do it sometimes, mainly if I'm bored during the mash. :blink: It's never been come back black near the time I would have finished the mash anyway, and I've only done it for fun. (Note to self: Get out a bit more.)


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## Mr Bond (29/6/07)

Stuster said:


> I'll do it sometimes, mainly if I'm bored during the mash. :blink: (Note to self: Get out a bit more.)



I'm never bored for that 90 mins,I'm either fixing brekky for or supervising kids baths,or supervising tea and tucking the buggers in so i can start the sparge in peace.2night is a rare occasion with the wife home, so I'm AHB'n


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## Online Brewing Supplies (29/6/07)

Thirsty Boy said:


> I do one if I have done something unusual where I think conversion might be effected.
> 
> Lots of adjunct, larger than usual sourmash, dodgey or new/unusual malt...
> 
> ...


I can see this being one of those point of view things."Iodine doesnt go black not nessesarily honky...."I have to agree to a point.But the colour of a iodine test will also indicate the presents of dextrines and starch.So you can judge to a point how your finished product will be.If it doesnt work why is it recommened in brewing texts?Yes I can tell by looking at my mash that I think I have conversion BUT I still check to see the colour of the reaction.In simplified terms check out Greg Noonans Brewing Lager pages 143-144 You will see were Im going on this point B) .


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## Kai (29/6/07)

Gryphon Brewing said:


> I dont follow your thoughts.What is RDWHAHB got to do with it.Not very scientific.Each to there own.I do it because I want to reproduce good beer and cut down the variables.Not saying you dont produce good beer :super: but its the way to remove F ...ups.Every time you get new malt it is different in it parameters so a it was good last time approach is not good.All breweries do regular testing on all variables water, malt, hops and just about any thing you can think of.How would you feel if I sold you skanky malt? These tests are for good reason. B)




No, it's not very scientific, but that's the way I like it. I think as homebrewers we're all guilty of sweating the small stuff too often. My point was that an iodine test is not something you ought to feel obligated to do every batch you brew. Just do it if you're worried, but don't take an all-clear on the iodine to mean you have a perfect wort.


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## johnno (29/6/07)

I barely have time to scratch my arse.
Let alone do an iodine test.


cheers
johnno


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## Tony (29/6/07)

whats iodine ?

i guess that a NO.

bugger that.

I use my refract and watch the Brix go up. when they stabalise its done.

works for me 60 to 90 min mash works fine. I cant see any point in testing with iodine and ending the mash early at say 40 min if you get a reading that tells you its done.

I dont trust it anyway, its to......dodgy kitchen crack lab technology for me

cheers


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## Online Brewing Supplies (29/6/07)

Kai said:


> No, it's not very scientific, but that's the way I like it. I think as homebrewers we're all guilty of sweating the small stuff too often. My point was that an iodine test is not something you ought to feel obligated to do every batch you brew. Just do it if you're worried, but don't take an all-clear on the iodine to mean you have a perfect wort.


I can see your point of not sweating on the small stuff but I bet you phifty bucks later on in your brewing expierence that you will be saying that same as me.Its one big learning curve and I like to pass on my experiences.Better to learn from others mistakes! B)


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## Kai (29/6/07)

So you think an iodine test is something a homebrewer should do every single batch?


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## Ross (29/6/07)

Is there any purpose of doing an iodine test if you mash for 90 mins. If it turns black do you mash for another 30 mins? I've tested a few times out of interest, but can't really see the point when doing a 90 min mash as I do.

cheers Ross


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## Online Brewing Supplies (29/6/07)

Kai said:


> So you think an iodine test is something a homebrewer should do every single batch?


As a learning tool yes ( I still do ).But as I said you can still produce good beer with out one.The main factors being a change of malt (batch numbers) change in mash profile and additional adjuncts.Its a bit like doing final pH to indicate infections( 4.1-4.3).But thats another thread.You dont have to agree just listen and make up your own mind.Thats what its all about. It not crack tech but founded in science.


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## Gerard_M (29/6/07)

Iodine tests are very important, I did one in November 2002. I may do one again, but no great rush at this stage.
Cheers
Gerard


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## Online Brewing Supplies (29/6/07)

Gerard_M said:


> Iodine tests are very important, I did one in November 2002. I may do one again, but no great rush at this stage.
> Cheers
> Gerard


Good one! :super:


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## AndrewQLD (29/6/07)

Gerard_M said:


> Iodine tests are very important, I did one in November 2002. I may do one again, but no great rush at this stage.
> Cheers
> Gerard



Gerard, it is quite possible that at this stage your Iodine may well be past it's use by date. If that is the case you may need to buy another bottle. However don't become alarmed as I have heard that if you mash for 20 minutes conversion will be complete and all will be well. I wish you luck with your search for Iodine.

Cheers
Andrew


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## Zwickel (29/6/07)

I do it only if I try out something new. As long as I do my usual batches, I dont need doing the iodine test anymore, but if Ive changed something, like doing a single rest for my next batch, of course Id like to know how it turnes out.

Fore example, short time ago my mash out temp was overshooting, went to 87C, so I was curious to see if something has changed, i did the iodine test and it showed a slightly darkened changeover.
Of course it has no consequences, its just to know it.

Cheers


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## tangent (29/6/07)

if i'm doing a high adjunct brew, i think about doing one, especially as Stoutdrinker gave me the stuff to try it. then i have a beer instead.


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## Online Brewing Supplies (29/6/07)

Zwickel said:


> I do it only if I try out something new. As long as I do my usual batches, I dont need doing the iodine test anymore, but if Ive changed something, like doing a single rest for my next batch, of course Id like to know how it turnes out.
> 
> Fore example, short time ago my mash out temp was overshooting, went to 87C, so I was curious to see if something has changed, i did the iodine test and it showed a slightly darkened changeover.
> Of course it has no consequences, its just to know it.
> ...


I dont know about that program you are running but to over shoot by that much.Not at my place. I would be more looking at the pH that you had at last runnings.This will affect the beer drastically What style were you making?Astringency will be a more of concern at this temp over run.
Gryphon Brewing


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## berazafi (29/6/07)

Gryphon Brewing said:


> I dont know about that program you are running but to over shoot by that much.Not at my place. I would be more looking at the pH that you had at last runnings.This will affect the beer drastically What style were you making?Astringency will be a more of concern at this temp over run.
> Gryphon Brewing





I think with todays modified malts there would be absolutly no reason to do it, you would have more chance of having your temp meter not give you the correct reading than have a bad batch of malt



Do you calibrate your gear before every brew, if not i think you could probably also do away with this test also


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## Zwickel (29/6/07)

Gryphon Brewing said:


> I dont know about that program you are running but to over shoot by that much.Not at my place.


hahaha, youre kidding  
it was my own fault, Id disconnected the temp probe already before the program has finished, but didnt consider that the gas burner starts again when the temp drops.


> I would be more looking at the pH that you had at last runnings.This will affect the beer drastically What style were you making?Astringency will be a more of concern at this temp over run.


The PH is just fine, we have very soft water here, perfect for a Pils. The mash PH is always around 5.3 to 5.4.
That beer(a Pils) is still in cold conditioning, not yet ready to drink, Ill see how it turnes out.

Cheers


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## Online Brewing Supplies (29/6/07)

berazafi said:


> I think with todays modified malts there would be absolutly no reason to do it, you would have more chance of having your temp meter not give you the correct reading than have a bad batch of malt
> 
> 
> 
> Do you calibrate your gear before every brew, if not i think you could probably also do away with this test also


 Yes I do calibrate my pH meter every brew.And this is not a cheap (mine $600.+) hand held meter. all temp readings are verified. But we are getting off the point.:Every one says modified malt as if it is a protection against bad brewing techniques. Not the case.Malting has taken a giant step forward but it will not protect you by quoting "modified malt":.You still need to use the malt to your predicted outcome.To use and to know the malt will get you part way there.Then its up to you to use the knowledge to your advantage.


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## johnno (29/6/07)

Gryphon Brewing said:


> Yes I do calibrate my pH meter every brew.And this is not a cheap (mine $600.+) hand held meter. all temp readings are verified. But we are getting off the point.:Every one says modified malt as if it is a protection against bad brewing techniques. Not the case.Malting has taken a giant step forward but it will not protect you by quoting "modified malt":.You still need to use the malt to your predicted outcome.To use and to know the malt will get you part way there.Then its up to you to use the knowledge to your advantage.




All good and well.

I will use my $600 pH meter when I am running my own brewery. (In my dreams and something I do not really want to do)

I got into this hobby to make great tasting beer. I can do that without worrying about iodine tests, pH levels etc etc, as a matter of fact I dont really care about the scientific side of it that much at all. 

I know that I can add so much water at a certain temp to such and such malts and make a particular beer. That is the bottom line for me. If I do not extract every last bit of fermentable sugar drom the grain that is still ok with me.

Modern day malts are modified enough for people like me. 

cheers
johnno


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## berazafi (29/6/07)

Gryphon Brewing said:


> Yes I do calibrate my pH meter every brew.And this is not a cheap (mine $600.+) hand held meter. all temp readings are verified. But we are getting off the point.:Every one says modified malt as if it is a protection against bad brewing techniques. Not the case.Malting has taken a giant step forward but it will not protect you by quoting "modified malt":.You still need to use the malt to your predicted outcome.To use and to know the malt will get you part way there.Then its up to you to use the knowledge to your advantage.





Fair enough, but i think you may be have a little OC disorder and maybe some shares in the iodine industry, but each to there own


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## Online Brewing Supplies (29/6/07)

Zwickel said:


> hahaha, youre kidding
> it was my own fault, Id disconnected the temp probe already before the program has finished, but didnt consider that the gas burner starts again when the temp drops.
> 
> The PH is just fine, we have very soft water here, perfect for a Pils. The mash PH is always around 5.3 to 5.4.
> ...


Hi To have soft water, you lucky person. What style beer works best for your water profile /Pils yes!
and using the finished beer pH not the wort pH. If you have a finish pH above 4.3 you have to start looking at process control or infections.But I know this would not be right in your case.  just to make a point.


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## Online Brewing Supplies (29/6/07)

berazafi said:


> Fair enough, but i think you may be have a little OC disorder and maybe some shares in the iodine industry, but each to there own


OC disorder? Ac's are not my forte.what are you saying.


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## Online Brewing Supplies (29/6/07)

johnno said:


> All good and well.
> 
> I will use my $600 pH meter when I am running my own brewery. (In my dreams and something I do not really want to do)
> 
> ...


And its fine if you dont want to listen to free advise.I only put this here from experience not from being a smart arse.I also got into this to make great beer.But science got me to making better beer.


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## Kai (29/6/07)

Gryphon Brewing said:


> As a learning tool yes ( I still do ).But as I said you can still produce good beer with out one.The main factors being a change of malt (batch numbers) change in mash profile and additional adjuncts.Its a bit like doing final pH to indicate infections( 4.1-4.3).But thats another thread.You dont have to agree just listen and make up your own mind.Thats what its all about. It not crack tech but founded in science.




Yeah, pH is another thread, probably where I'd say homebrewers don't need to spend hundreds of dollars on pH meters either  

I'm not arguing the scientific basis of your viewpoint, it's just I don't think it's an important thing for us to worry about. Get the fundamentals right and fretting over conversion ranks somewhere close to worrying about whether or not a meteor strike is going to ruin your brew day.


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## Mr Bond (29/6/07)

johnno said:


> I know that I can add so much water at a certain temp to such and such malts and make a particular beer. That is the bottom line for me. If I do not extract every last bit of fermentable sugar drom the grain that is still ok with me.
> 
> Modern day malts are modified enough for people like me.
> 
> ...



Onya Johno


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## johnno (29/6/07)

Not trying to be a smatarse.

I shall rephrase that. I dont have a much of a clue about the science side of it.

See..this is the great thing about brewing. You don't have to understand how it works in great detail. Just that it does.

Sort of like the first people that accidently discovered beer.

ferment and drink. mmm..

cheers
johnno


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## Online Brewing Supplies (29/6/07)

johnno said:


> Not trying to be a smatarse.
> 
> I shall rephrase that. I dont have a much of a clue about the science side of it.
> 
> ...


 total agree.Science just makes it better for me!

long shall we brew.mmmmmmmmmmmmm


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## Online Brewing Supplies (29/6/07)

Kai said:


> Yeah, pH is another thread, probably where I'd say homebrewers don't need to spend hundreds of dollars on pH meters either
> 
> I'm not arguing the scientific basis of your viewpoint, it's just I don't think it's an important thing for us to worry about. Get the fundamentals right and fretting over conversion ranks somewhere close to worrying about whether or not a meteor strike is going to ruin your brew day.


 And some one said the earth was flat. Dont know where that came from.Ducking from meteors!


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## Mr Bond (29/6/07)

Curiosity has got the better of me GB.
You are tagged as a retailer,but your profile has no links to any websites.
Are you a HBS guy or a brewer at a micro?Your level of interest in all things technical says you are more than an average backyarder.


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## Online Brewing Supplies (29/6/07)

Mr Bond said:


> Curiosity has got the better of me GB.
> You are tagged as a retailer,but your profile has no links to any websites.
> Are you a HBS guy or a brewer at a micro?Your level of interest in all things technical says you are more than an average backyarder.


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## Gerard_M (29/6/07)

AndrewQLD said:


> Gerard, it is quite possible that at this stage your Iodine may well be past it's use by date. If that is the case you may need to buy another bottle. However don't become alarmed as I have heard that if you mash for 20 minutes conversion will be complete and all will be well. I wish you luck with your search for Iodine.
> 
> Cheers
> Andrew




Thanks for the tip Andrew, I will grab another bottle in the next Iodine bulk-buy!
cheers
Gerard


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## Whistlingjack (29/6/07)

Any maltster that is a worthy supplier will publicise the iodine test results of his product. This makes it easy to estimate the conversion time of the starch.

Therefore, with this information, its not necessary to test each time with the same malt. Having said that, its wise to conduct a test with each new malt, taking samples from the mash every five minutes.

I do it, because I can...

WJ


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## Online Brewing Supplies (29/6/07)

Mr Bond said:


> Curiosity has got the better of me GB.
> You are tagged as a retailer,but your profile has no links to any websites.
> Are you a HBS guy or a brewer at a micro?Your level of interest in all things technical says you are more than an average backyarder.


I was brewing as a micro guy. I have studied brewing.I am going to do a retail thing In a few weeks (gryphonbrewing.com.au )but on a all grain basis only.And yes I am a back yarder as well.I enjoy the back yard brewing the best.So you have found me out .well done Mr Bond.


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## Online Brewing Supplies (29/6/07)

Whistlingjack said:


> Any maltster that is a worthy supplier will publicise the iodine test results of his product. This makes it easy to estimate the conversion time of the starch.
> 
> Therefore, with this information, its not necessary to test each time with the same malt. Having said that, its wise to conduct a test with each new malt, taking samples from the mash every five minutes.
> 
> ...


 So do I! but do you trust what the malt seller (supplier) tells you ? Maltsters are different.how are your brews going?Getting cold down there,must be good for a pils.Are you at Tangle Head or back yarding?


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## rough60 (30/6/07)

Hey guys,
I started AG around 6 months ago, I had planned to do an iodine test with my first batch but my first AG day was so hectic that I forgot. After 2, sometimes 3, batches per week for the last 6 months, seeing this thread is the first time I've thought about it again, and probably the last.
Cheers.

edit: spelling


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## Barry (30/6/07)

Good Day
I do a 90 minute mash to make sure it is all converted and have breakfast/read the paper.
A fellow home brewer tried 15 to 20 minute mashes and all converted (tasted his beers) but they were all malty with lower than normal ADA. Tasted very good but were fuller than normal for style.
I will test every blue moon and seeing there will be a blue moon tonight I better test the mashes tomorrow. :beer:


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## SpillsMostOfIt (30/6/07)

I did an iodine test once and failed so dismally I decided to give up on the whole iodine thing entirely... :blink:


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## matti (30/6/07)

one day ....maybe...


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## Weizguy (1/7/07)

Gryphon Brewing said:


> And some one said the earth was flat. Dont know where that came from.Ducking from meteors!


Is that you, Darren?



Sorry, Darren. I couldn't resist.
GryphonBrewing, you have been quite vocal lately. Are you trying you get your post count up, or are you taking it a little too seriously?
Before you get fired up, I realise that brewers are a passionate lot and I also feel the need to testify on occasion, but U gotta let people know why you are spouting copiously.

Back on topic, I performed an Iodine test yesterday with a drop of Betadine, and it was a negative result. I was hoping that I might be able to explain the excessive cloudiness of my Gose with a starch haze, but no...my conversion was good, and so was my attenuation. I'm gonna have to blame it on the low flocculation of the WLP380, and maybe the overnight/sour mash before I did the protein rest and main conversion rest.

As you say, the Iodine test indicates conversion/removal of starch and nothing else. It doesn't let you know the levels of dextrins or proteins or lipids (new word for some brewers).

However, I'd highly recommend a starch conversion test by using Iodine to all new all-grain brewers for three reasons:
To be sure that you have made a wort that will be free of starch haze,
To be assured that starch will not give any bugs something to eat after the yeast has attenuated the malt,
and, the _reassurance_ that you have fully converted your mash/grist.
Beerz
Seth


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