The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

The Ultimate Proofing Box!! (and hi)

  • Pin It
CaptainNemo's picture

The Ultimate Proofing Box!! (and hi)

Hi all,

I've been feeding and maintaining a starter now for about 5 months and haven't made a single loaf! Now I'm in winter, wanting to actually make some bread and  proofing is hard to do in this freeeezing house so I've decided to build a proofing box. .

In light of this, I was wondering what would be a wish list of features for a proofing box... Having no experience with breadmaking but a lot of experience in electronics  I think I can pretty much implement any feature I just dont know what they should be . Obviously temperature control would be important but what else? humidity control? programmable temperatures over time? airflow control?

Cheers! :D

PeterS's picture

Humidity control could be done via simple evaporation in a small box; 5-10 cubic ft, I'd guess. Any larger and you might consider some kind of heating element. A small box might not even need a fan, but it would probably better with one. A larger box will need a fan and maybe some kind of ductwork.

Nice PID controllers can be had on the cheap from ebay, craigslist (sometimes) and the like. There are several very inexpensive humidity sensors available on the market (many using Humirel sensors). I don't think you'll need a ramp or soak profile. Some have both humidity and temperature outputs. That and a relay for a heater and you're good to go.

Google proofing or holding cabinet. That will give you an idea what is available commercially; you can scale it down from there. With your background you should be able to do the cat's pajamas.

CaptainNemo's picture

Thanks for the tips. The actual implementation should be okay I was more wondering what features I should implement. 

For the technical side of things I was thinking to build an insulated box, fit one of these breakout boards for feedback, interface it to a micro and control temperature with a PWM controlled peltier. I was thinking to also fit a countdown timer which can reduce the temperature after a particular (adjustable) time to retard the growth.

Cosmetically I was thinking to have two brushed alumnium dials on the front controlling the temperature and humidity settings. small 16X2 LCDs or possible a pair of double digit 7 segment displays.

Either way, I'll document it and post all the schematics etc in case anyone is interested :)

Thanks again :)

PeterS's picture

only on a larger scale: converting an enclosed sheet pan rack to a proofing cabinet.

I have one of these:
and I'm going to use a watlow 93 controller that I bought off of ebay to control it; it was only $33 shipped, couldn't touch that making my own.

However, because I am having so much fun playing around, I think I'm going to check out some of the discrete humidity sensors with an Arduino. What micro are you planning on using?

Do you have a spec sheet for your peltier. My cabinet will be in a basement that doesn't get above 70F in the summer and is probably 50-60F in the winter. That should provide enough cooling for the proofing cabinet--to work against the heating and keep the temp stable. For retarding, I'll buy an old upright freezer and convert it to a fridge.

And, if this isn't enough, then I'm going to add real steam injection to an old double wall oven.

CaptainNemo's picture

I completely agree, there is no way I could do a cheaper build than buying off the shelf bits on ebay but like you mentioned it is so much fun to tinker!

I'm planning to use an atmega128 header board from olimex for the simple reason that I have some around as I use them for work. More or less they are the  same type of chip as an Arduino just without the ease of use. Both of our ideas are still nice and overkill enough ;)

All my specs are really preliminary as I only decided I'd do this a week or so ago and didn't really know what, optimally, I should be designing.

The peltier modules I've been looking at areeee

The micro board is

Display most likely 16X2 like so


To be honest I have NO idea where I'll be keeping it though as I'm literally moving into a new house today so I don't know how stable temperature is in the house.

Please keep me posted on how you go!! :)

sheffield's picture
sheffield (not verified)

Search for proofing box on this site and you will get loads of good information.

HMerlitti's picture

Get a temp gauge.   Put it in your refrigerator.    Turn off your frig and insert the dough.   It gets to between 45 and 50 degrees.  Leave it there overnight and proofing is done.    The other stuff in the frig will not be harmed. 

Mini Oven's picture
Mini Oven


The other stuff in the fr--  will not be harmed.

Sorry to pounce on you, but that's not only an offensive misspelling of fridge, but refrigerators vary and letting the food warm up can do some serious damage to other foods in there.  Bacteria and yeasts will not only grow in the dough but in other food as well!

Yerffej's picture

Mini makes a very valid and important point here.  While it is common to get away with less than perfect food handling on many occasions, one need experience food poisoning only once to know that diligence is of the utmost importance when handling and refrigerating food.  Personally, I would NOT let my refrigerator warm up as described other than to defrost and clean the beast.



PeterS's picture

but the food in the fridge is probably going to be at lower temp than the air temp within for this relatively short period of time. This is not unlike the conditions that one encounters with a power outage. If the ambient temps aren't too high, the contents of the fridge can survive just fine for hours; the fridge should not be opened, of course, in the interim.

That said, the bigger issue to me is: what kind of proofing is desired here, high or low temp? The former will, of course, occur faster, the latter would actually be retarding and produce a sour-er loaf. I'm looking for a constant 70-75F. 

Using a fridge as a proofer/retarder this way is also very energy inefficient; but, and, probably most undesirable of all, we would not have all the fun of creating a highly sophisticated overengineered piece of home baking equipment. :)

HMerlitti's picture

Offended by a perceived misspelling?   Interesting.   You must not have a lot to do. 

BTW, I tried a couple spell checkers, and, according to Microsoft and Wikipedia  you're wrong.  They list it as a noun.   

However, I did not know about the profane use of the word as a verb.    

(v. frigged, frig·ging, frigs Vulgar Slang. 1. To have sexual intercourse with. 2. To perform an act of masturbation on. v.intr. ...)

Very good Mini   !!!      

However, with better things to do, I would like to get back to the subject.   Europeans/Italians for years wondered what the fascination was with refrigerators.  They often let food sit out all day long.

Secondly, my/your frig now is at 38-42 F.    I am only talking about letting it get to 48 F over night.   As mentioned above, it holds there if you do not keep opening the door.  

There is much written info on the desired sour acid that develops at around 48 F.  


rossnroller's picture

Mini's use of the word 'offensive' in relation to your misspelling of 'fridge' may just possibly have been humorous in intent. Pls consider!

And let there be no doubt - 'frig' is not a "perceived" misspelling! It is an actual mispelling. The word is 'fridge'; 'frig' it most certainly is not! Hence your confusion about "the profane use of the word as a verb." You're referring to a different friggin' word (standard punning apologies apply).

If you didn't find the word 'fridge' in Microsoft (?! I won't ask) and Wikipedia, that's probably because (a) they are not dictionaries and (b) 'fridge' is an abbreviated form of 'refrigerator' that has now morphed into common use as a word in its own right.

So, on this occasion you're wrong and Mini is right! And where do I come in? Well, as a pro freelance copy-editor for over 20 years, I am a pedant when it comes to spelling and grammar (although I delight in breakin' the rools myself with all manner of perverse spellings, neologisms and manipulations of the langwidge). You think I can resist commenting on a point like this?


HMerlitti's picture

It is fun when people get their panties in a bunch over this minutia.   Probably why Seinfeld did so well. 

Sorry, I just copied what was on the internet (not always a good source), however, it was clear, "frig" is also a verb, "to frig", as I read it.   So, don't blame me.   Information is there to be absorbed.   I am just the messenger. 

And, I only looked it up once and feel that additional research at this time would not be as much fun. 

Mini still should be congratulated and I will use this newly learned verb with others  and make them go look it up. 

And, I am truly sorry about the morphing.  Unfortunately that is why children today get away with improper U. S. English too often permitted in schools and books.   Again, it is not my fault.   I think there should be stricter standards. 

And, it is good to meet, finally, a writer that cares about writing and is good at it.   Keep up the good work. 

p.s.  Went back to look for humor.   Didn't see it but, I'll take your word for it.   May be she will correct me, again. 

rossnroller's picture

Seems you're still not prepared to take responsibility for your error! As you say, 'frig' is a verb (slang) - but the word you misspelled is 'fridge'. The two words are not related. So yes, I AM shooting the messenger - cos he got the message wrong! Don't blame me. I'm just the executioner.

PeterS's picture

right here:

Let's get back to the subject at hand, please...

rossnroller's picture

Had no intention of hijacking the thread - just a light-hearted aside. All over now, so back to the topic.

HMerlitti's picture

What would one have in the frig that would go bad at 48 F    in 8 hours ??    Just asking.

Kymh, do you want to add your comment ???

crabapplefarm's picture

Couldn't you buy a used refrigerator (or get a nonworking one for free)?  If you have the space, this would seem the best solution.  If you're working small batches, a dorm sized refrigerator would probably work. too.  Either way, you could have a dedicated "appliance" that you could alter to fit your needs.