Starter smells like paint! :(


Help! Hey, did you guys just start this forum? First thread, what an honor! Thanks for running it.

Anyway, this is thursday morning US time, and I started making a new starter from scratch last sunday nite. I used regular white flour (bleached) and tap water, 4:3 by volume. I know rye and whole wheat are better, but I thought I would try it this way. I know I'm a rank beginner, I know it's harder this way, but please humor me for now. I'm not a sourdough connoiseur, I just like good food and chemistry/biology experiments.

I've kept it constantly around 80-85 degrees by my thermometer . On monday the batter started showing some tiny bubbles and smelled like sourdough. Tuesday it didn't smell as good, so I fed it a little. Wednesday same thing, fed it more. Some authors say feed immediately & feed a lot, others say wait until it gets active. So far there were only a few tiny bubbles, no froth or expansion.

Last nite and this morning, it had a smell very much like paint. Yuck. I've been worried that feeding an undeveloped starter is only diluting yeast that is still in the latency phase, so I didn't want to feed it too much. But now my plan is to feed it more. I'm adding 1/3 c flour and 1/4 c H2O to 1/2 c starter, every 12 hours, starting this morning.

Any comments? Other than get better flour? These are my main questions:

1) Does anybody know what is causing the paint smell and/or what it indicates?
2) One theory that occured to me was why not grow the yeast/lactobacilli in the same flour they will be baked in, to get the best strains for that flour. Does that make any sense at all, or no?

Thanks for any/all responses.

302 users have voted.


Graham's picture
Graham 2005 July 2

Hi SourGeek.

Yes..the forum is only a few weeks young. Congrat's on the first post.

Your problem with the starter is not uncommon. My first suggestion would be to start again with a thicker brew..less water. A consistency that can just be stirred with a spoon...or possibly even a little may have to use your fingers to massage it (don't make it too hard!).

Leave this mix for longer, say 24 to 48 hours. The stiffer the mix the longer you will have to wait. Some aeration and a yeasty smell should occur. Mix again briefly. Leave 12 - 18 hours and then this starter could be ready to innoculate a wetter mix of flour and water..which can eventually become the leaven for your final bread dough.

Try keeping it closer to 80 F (26.6 C) or even as low as 72 F (22.2 C). If you are having trouble with thinner (faster) hotter (faster) starters, the concept here is to slow it down and get more control. It is something I would try..not a guarantee it will work for you!

It could be worth taking a very small amount (up to a teaspoon) of your first attempt and adding that to your second brew. If it smells nasty leave it out altogether (empty the old brew into your compost).

Use filtered water or rain/spring water. Use a ceramic or glass container for the starter. Food-grade plastics also work..but starters are generally small so it's easy to use a tea cup, cereal bowl or similar, keeping the brew away from plastics and steel while you can (big ceramic vessells are hard to find/handle for larger brews).

You noted that your flour possibly wasn't suitable. Most flours, even white and not organic, are capable of attracting a level of yeast activity. However if at all possible, find some flour that at least smells wholesome when you open the bag and sniff.

The paint smell? I would like to know if there is even a hint of this smell shortly after wetting the flour. I suspect is it a characteristic smell of the flour..aromas intensified when wet. Possibly it's a residual smell from the chemical treatment of the flour. But really can't say.

Hopefully further replys will help. Good luck.

SourGeek 2005 July 4

Thanks for responding.

[b][color=darkred]the forum is only a few weeks young. Congrat's on the first post.[/color] [/b]

Boy, your timing is perfect. It seems my kitchen has been taken over by toxic mutant organisms.

[b][color=darkred]My first suggestion would be to start again with a thicker brew..less water. [/color][/b]

What are the reasons for that? What advantage does the thicker batter have for growing yeast? Do bacteria have more trouble in a dry environment than yeast? Why do some recipes call for 1:1 by volume? I started using 4:3, now I'm using 3:2 by volume.

[b][color=darkred]... this starter could be ready to innoculate a wetter mix of flour and water..."[/color][/b]

Interesting. Why would you start thick and then go thinner?

[b][color=darkred]Try keeping it closer to 80 F (26.6 C) or even as low as 72 F (22.2 C). If you are having trouble with thinner (faster) hotter (faster) starters, the concept here is to slow it down and get more control.[/color][/b]

What benefit does control get you? What kinds of organisms grow better at or below 80 degrees? I thought 80-85 was optimal for yeast, and lactobacilli preferred 90.
(got that from [url=]What factors affect microbial growth?[/url])

[b][color=darkred]The paint smell? I would like to know if there is even a hint of this smell shortly after wetting the flour.[/color][/b]

No. When I stir & sniff a fresh batch of flour+water, it smells like wet flour.
The starter is active now. Here's how it evolved:

days . temp . . . smell . . . . . . comments . . . . . . . . . . . starter . . flour . . H2O
1 . . 80-85 . . sourdough . . . . . . yum! . . . . . . . . . . . . . . (didn't feed)
2 . . 80-85 . . not so nice . . . . . . . . . . . . . . . . . . . . . . . (fed some, but didn't
3 . . . 85 . . . . . paint . . . . . . . . . . ick! . . . . . . . . . . . . . . . . write down how much)
3.5 . . . . . . . . . . " . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1/2c . . 1/3c . . 1/4c
4 . . . 85 . . . . . . . . . . . . active, fluffy like meringue . . . . 1/4c . . 1/3c . . 1/4c
4.5 . . 80 . . . fiberglass . . . . not as bad as paint . . . . . . ~1c . . 1/3c . . 1/5c
5-7 . 70-80 . . . . " . . . . . . . . MAYBE not as much . . . . . . 1/4c . . 1/2c . . 1/3c . once per day

Does anybody know what would generate those smells? I've only found two references on the net. They say

[url=]Toss any starter that turns orange or pink and develops an unpleasantly acrid odor. The color and smell signal the presence of undesirable bacteria.[/url]

[url=]if the starter doesn't bubble, produces a strong unpleasant odor, or becomes an off color such as pink, an undesirable yeast has taken hold, and the starter must be discarded.[/url]

So is it yeast or bacteria? The color is fine. The smell is unpleasant, but I'm not sure I would call it "acrid", which I think of as biting or acidic. Another source says

[url=]Ed Wood ... writes that contamination “sometimes, although rarely, occurs.” It’s happened to me both times I’ve used his cultures. Two out of two seems a lot more frequent than “rarely.”[/url]

So I would prefer to find out what the problem is and how to suppress it by adjusting the environment, since I expect it to be a continuing threat, rather than grow the same problem all over again.

Thanks for the help!

Graham's picture
Graham 2005 July 5

Hi again SourGeek

The stiffer, cooler dough will reduce activity of both yeast and bacteria. Stiffer, cooler doughs slow down the rate of lactic acid production from bacteria allowing acetic acid production to compete.

While many yeasts do not enjoy acetic acid, remember that we are talking about a starter and not a fully fermenting leaven. The starter begins with a very limited colony of yeast and bacteria. There is initially not the quantity of bacteria required to produce an acidic, poisonous environment for yeast. (A stiff dough does however reduce the availability of nutrients via fluids).

I can't tell you exactly how long you have with a stiff, cool dough before it is toxic to yeast. But my intuition tells me that you have nothing to worry about for at least 24 hours and possibly as long as 48 hours if you keep it closer to the early 70's (deg. F).

You have actually done more research than me in this area...I will have to take a closer look though it does confirm that bacteria tolerate acidic environments where yeasts have difficulty. Worth a read..[url=]What factors affect microbial growth?[/url]..but for now..

I have found a section in a book given to me by Alan Scott, The Bread Builders (Daniel Wing and Alan Scott). On page 58, Daniel Wing (I assume) talks of a similar process and suggests 60 to 65 deg. F. This sounds fine to me and is probably more suited to the full 48 hour time frame.

At that point I would reccommend you take your tiny, innactive colony and introduce it to a new, more fertile environment. Warm the brew up..but not to optimum temperatures yet. Ensure adequate food (quality flour) and a medium to disperse nutrients (quality water). Acidity is also reduced.

If you don't want to have a huge brew on your hands, you could toss some of your initial stiff mix away, into the compost. A ping-pong ball quantity of stiff starter into 1 cup of thick but stirrable batter. Mix it together at 72 to 80 degrees (22 to 26.6 C).

Give this mixture a further 12 to 18 hours and you might call it a sponge or leaven. But more likely it will need one more cycle (12-18 hours/depending on temp, stiffness, flour type, water quality and some others that I have forgotten - it's late) to be a truly active leaven.

In summary, there is no need to aim for optimum temperatures and flour/water ratios from the very start. Start the process gradually and you are less likely to catch undesirables.

From your table of events it appears that starting at too high a temperature could have let you down. I say could because on another day in another town it could have succeeded. It would be good to identify that smell. The net is letting us down in that regard.


Note: Could it be alcohol? Acetic acid (fruity smell...I guess not?). Lactic acid is a warmer sensation..which you could describe as "yum" but would be unlikely to be smelling it on day 1.

Graham's picture
Graham 2005 July 5

I should point out that when I said it might need one more cycle of 12-18 hours...a part of this new cycle is a major fresh component of flour and water. eg. only 25% of the mixture would be the original, active brew. The rest is fresh. Again..there are variables (some already mentioned)...I am trying to keep it workable.

The first time I ever saw sourdough being made was when a French friend of mine left a batter in a jar overnight next to her wood stove. She used that mixture to leaven bread the very next day after only one nights brewing! (I suspect there must have been some baker's yeast in there somewhere). It can't be that easy..can it?


SourGeek 2005 July 5

Hi Graham, thanks for posting.

You've said several things about starting out dry and cool. I've been trying to figure that out, and the only explanation I can think of is that the yeast has to go through its latency phase. If that phase is relatively insensitive to water and heat, then it would make sense to keep the starter dry and cool while the yeast "wakes up", to suppress bacteria that are already mature. Does that sound reasonable?

[color=darkred][b]Stiffer, cooler doughs slow down the rate of lactic acid production from bacteria allowing acetic acid production to compete.[/b][/color]

Supposedly, acetic acid is bad for yeast. What are the reasons someone might want acetic acid? The only one I've seen is that it boils off during baking, so the bread won't taste as sour.

[color=darkred][b]Could [the smell] be alcohol? Acetic acid (fruity smell...I guess not?). Lactic acid is a warmer sensation..which you could describe as "yum" but would be unlikely to be smelling it on day 1.[/b][/color]

No, definately not ethanol. I also posted this on a [url=]microbiology forum[/url], you can see more (unappetizing) nitty-gritty there.
The early smell was like sourdough, I have no idea whether that would be lactic or acetic.

I just started a second starter with unbleached bread flour. We'll see how that does. Also, I'm letting it sit at room temp, whereas the first one, I originally thought I was supposed to keep it warm.

And one final question: I've been wondering about rye flour. Suppose I would like to use a small amount of rye flour somewhere in the process. I see three points where it can be added: in the starter, the sponge, or the final dough. What are the differences between those three methods, in terms of flavor, speed, or anything else? It seems like they should be significant. I love rye bread, and I'd like to make the best use I can of a cup or less per loaf.

Graham's picture
Graham 2005 July 5

Rye is usually used as the sponge. The level of fermentation in a sponge reduces the doughs ability to develop a structure that can hold gas. Wheat is much better at forming a gas holding structure through its gluten forming proteins. Rye does not have the same ability so it has less of an impact on the overall strength of a dough if it is used as leaven rather than the wheat.

Preserving the strength of the dough is an issue but just as important are the amazing fermentation and flavour qualities of rye. Compared to wheat of same growing/milling quality, rye ferments faster. Here is where I quote from Baking, The Art and Science, 1988: Rye flour contains: less starch, less swollen protein, more soluble sugar, more water-binding semiliquid substances, more starch-digesting enzymes.

For those reasons it works very well as a starter too. Rye starter...ahhh..such an intense, stupefying aroma.

SourGeek this discussion has shown a need for a distinct Microbiology category in this forum. It is an area that fascinates and perplexes many a sourdough baker. Baking is so tactile. Sometimes the science is only called upon in desparation when failers occur and no clear explanation is available.

Of course there is an explaination and no amount of banging your head against the dough bench will fix 80 loaves that failed to spring in the oven.

So I hope you don't mind if I move this topic to the Research part of the forum, where I am creating a new heading...Microbiology. There's something I've wanted answered for many years and it has to do with an issue you talked about in your last post. So I will post there soon, or possibly you will beat me to it.

Please keep an eye out and be certain to publish any findings from you research. We are looking for interesting bits to publish on the [url=]RESEARCH[/url] pages of this have been uncovering juicy bits already.

Also I think that your latency phase proposition is likely to be correct.


SourGeek 2005 July 6

[color=darkred][b]Rye is usually used as the sponge.[/b][/color]
Thank you, that's very good to know.

Okay, I came up with another reason for making your starter thick, assuming yeast flourishes in a relatively dry environment while bacteria prefer wet. Is that true?

If so, then first of all, the dry starter more closely resembles the flour that supports the yeast, and is less hospitable to the bacteria. Second, any time you feed a starter, you're adding more yeast in the flour, and bacteria in the tap water. Obviously you would want to introduce more of the thing you want, and less of the one you don't want! So there's another wild guess for whatever it's worth.

SourGeek 2005 July 7

Wow, it's like this entire forum is my own personal blog. I think I'll call it "SourBlog".

[color=navy][b]SourBlog 6 July 2005[/b][/color]

Started feeding the paint mutant unbleached bread flour instead of chlorine-infested white flour. The paint/fiberglass smell is much fainter now, although not gone entirely yet. No sour smell either, it just keeps bubbling. This kind of makes me wonder why anyone would ever use bleached flour in any food product at all. The stuff is a biocide, isn't it? Currently shopping around for inexpensive unbleached flour.

Made a couple pizzas and a couple loaves of bread so far. Wow! With an egg sandwich on store-bought wheat bread, ketchup is a godsend to alleviate the sawdust flavor. With fresh bread made with baker's yeast, the ketchup seems harsh by comparison. With homegrown yeast, Yum! Yeast really DOES have flavor! I'll save the ketchup for hot dogs.

Veggie starter is still in the fridge, awaiting evaluation based on further reading whenever the library book arrives. In the meantime, there's still one loaf of bread left, and the recipe is being improved with each batch.

Anonymous 2006 March 4

Hi. I've got starter which has been active now for almost 8 months - it has always had a paint - like smell, from the beginning, but produces fabulous bread.

The starter was originally made using organic rye flour and after 2 weeks of rye I went over to feeding it with organic white flour. I take consolation that it doesn't smell like any common or garden paint, but the Farrow and Ball heritage range!

It is extremely active- will sit in the fridge for a couple of weeks untouched and revatalise instantly it is taken out and fed. So I shouldn't worry about the smell, if it does the job it is intended for.


Bill44's picture
Bill44 2006 February 1

Well a new starter of mine has the paint smell, has the yeast migrated from the states.

I started it on one of the hot days recently and it bolted, frothing right up. At its peak (12 hrs) I fed it and within 6 hours it appeard dead with a thick layer of hooch on top. Stirred and did a 1 Tablespoon 1 cup water 1 1/2 cup flour job and it continued to sulk, small activity, no hooch, but a definite strong oil paint smell. So you know where it went.

SourGeek 2006 February 9

Nice to see people posting here. Too cold now in the upper half of the planet to keep starter alive around here, but Spring is on the way.

Well a new starter of mine has the paint smell, has the yeast migrated from the states.

I started it on one of the hot days recently and it bolted, frothing right up.
Let's see, I started mine half a year ago, average trade winds run 10-20 knots, about 10,000 nautical miles . . . yup, should be there by now.

I found that rye flour was a big help in fighting off the paint monster. It seems to like high temps, so I kept my starter around 80-85F/about 28C. About a third rye in the starter, a quarter in the sponge, and a little more in the dough. It was always trying to come back, so that seemed to work best.

Bill44's picture
Bill44 2006 February 9

I've got a really good starter going now, after 3 trys, it tastes great and getting better all the time.

I've got a little setup ready for the colder months, I used a similar thing when I was brewing.
Basically it is a warmer pad, normally used for home brewing, onto which I have fixed the probe of a thermostat that is normally used in a chicken incubator. The thermostat is accurate to +/- 1/2 degreeC, place it in a suitable box and you're in business all year round.
Use your oven for rising, just turn on for 1 min or so and turn off again, should only need to do it every half hour or so.

It's a crying shame to lose a good starter just because of the cold, to say nothing of having to go all winter without a decent loaf of bread.

Fiddlerkelly 2018 November 24

I’ve had my starter about 10 days and in the last couple of days was just adding unbleached flour and tap water , today the starter started getting a paint odour. My starter was more runny before adding more flour and water so I decided to go back to half unbleached flour and half rye and added no water to thicken up the starter, hoping this will get rid of the paint like odour as I never had it the first week of the starter, am tempted to make a bun just the same to see how it taste .

oldman 2018 November 25

If you're noticing unusual, unpleasant odors you probably have undesirable bacteria growing.  You can try feeding through it.  As your starter gets firmly established it will create an environment that favors its own bacteria and crowd out the bad ones.  You can hurry the process along by washing the starter - thin it, pour off most of the liquid, throw out at least half of what's left then feed normally.  Since it's a new starter you could also try a one time feeding with 6oz unsweetened pineapple juice and 6oz flour.  The theory is that that will make the starter acidic enough that the paint-thinner bacteria won't thrive.

Fiddlerkelly 2018 November 26

Will try the pineapple juice just to see. When you feed your starter do you always add some rye with your white flour or just use the white flour with an established starter .

Fiddlerkelly 2018 November 26

Just made another loaf is stretchy but but a bit elastic, is this a matter of too much water or flour or something else. Then when I left it to rise for the first time the dough develops a bit of a doughy crust , any suggestions how to prevent this . The humidity her in my place is low .

SlackerJohn 2018 December 2

The best way to eliminate the possibility of too much (or little) of any ingredient, is to stick to a recipe.  :)

If you do that, you are unlikely to have MAJOR problems.


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