Decorized iodine

will decolorized iodine do the same as the original…i,m relitivly new to all grain and that what the drug store gave me…Thanks…

Is this for a conversion test? I wouldn’t even worry about doing one of those, unless your trying to save time. It’s easy to get false readings and decolorized iodine is not chemically the same as regular iodine.

I agree…save the iodine for cuts and scrapes. The whole conversion test thing is basically pretty much a waste of time.

I have been doing an iodine test using regular iodine from the drug store since starting AG brewing many years ago. Never really get a negative reading anymore but the test is simple and I always thought reliable. Just put a drop of the iodine in some of the cooled liquid from your mash and if it stays brown, your good. If it turns black no conversion.

So what am I missing about it not being useful? The little bottle of iodine is cheap enough and lasts for years.

What you’re missing is that it’s unnecessary. If you mash long enough at a proper temp, you’ll have conversion. And there are enough people who get false readings that I advise people to just skip it.

Denny, I agree. With today’s malts conversion is usually automatic, especially with a 60min mash. The only time I would worry is if I used a high percentage of adjuncts and didn’t have enough diastatic power. And, that’s not a malt problem, but a recipe problem.

If your doing it feel free to keep doing it but with the highly modified malts I feels it’s unnecessary.

Loopie, I’ve been doing all grain kits for three years and I’m about ready to start buying bulk grains. What is this diastatic powder you mentioned? Thanks

Diastatic power. The grains don’t contain enough (or any) of the enzymes needed to convert starch into fermentable sugars. The base grains that you buy in bulk will be fine.

To add further diastatic power is measured in degrees Litner or °L. Malts that will convert themselves have at least 30°L. Most base malts contain about 140°L per pound, which is plenty to convert most mashes (6-row contains much more, around 180°L!). However, if you use a mostly Munich base you may need to be careful as it only contains 40°-70°L for light (so I chose an average of 55°L) and 25°L for dark. This may not be enough diastatic power to convert.

The math is easy and goes like this:
Total= (°L x lbs) + (°L x lbs) / (total grain weight)

So say you’re going to use a recipe of 10lbs 2 row and 2lbs c40 it would look like this:
(140°L x 10) + (0°L x 2) / 12 = ~117°L. PLENTY to convert.

You only need to worry if you’re using a large portion of adjunct, unmalted, or specialty grains which contribute 0°L.

This is particularly problematic for partial mash Brewers who obtain most of their fermentables from DME/LME.


I guess it just gives me that warm fuzzy feeling knowing it converted. Can’t say I ever got a false reading though. How would you get one other than having too much of the grain in your sample? I do see black when the iodine contacts the grain hulls.

Guess I will just continue to do the test until my bottle of iodine runs out.