The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

bread proofing box

BobS's picture

Flour, water, salt, time, and temperature. The right combinations of those variables, plus technique, make good bread.

Along with a few simple tricks.

I've learned how to make pretty good bread from this forum. This is the first of a set of posts describing a few of the things I've learned. Maybe they will help somebody new.

Here in New Hampshire temperature can be a problem. Like this week when the overnight low was -6F and the temperature in our kitchen was 55F. Yeast growth is really dependent on temperature and there is a happy zone in the 70-80F range. A proofing box gives me the control over temperature. There are several threads on proofing boxes on TFL. and there are commercial products. I made one, mostly with stuff I had around the house.  It was one of the things that made a big difference in my ability to make consistent bread. Here it is in pictures.

I started with a cooler we had in the basement:

Any size will do, as long as it is 'big enough'. Then I added a 15W light bulb and socket, and a thermostat. Nothing fancy, just shoved it all in there. The extension cord coming out of the box is flat, rather than round, so it is not too badly squished. The light bulb could probably be smaller wattage. You do want it some distance away from the thermostat.

That's Earlene, my starter Fred's love child, bubbling in the middle after a warm and pleasant overnight stay. The thermostat is a Lux Pro PSP300. I got mine from Amazon:'s a little expensive, but it works well. I think their WIN100 model, which is a little cheaper, would work too.

I can also fit a proofing bucket for bulk fermentation in there:

Cambro buckets work very well for bulk fermentation. Make sure you get yours from a local restaurant supply rather than a 'bread enthusiast' web site: mine cost $6.

That's Hamelman's Five-Grain Levain, more or less, in there.

I usually retard my sourdoughs, for better flavor and scheduling. But sometimes I do the final proofing in the box. For that I built a little stand that lets me stack bread pans or bannetons.

The box is tight enough and the loaves are wet enough to create a nice humid atmosphere inside without the need to introduce additional humidity.

The thermostat works for both heating and cooling. Sometimes I use it to control a little portable electric cooler (which doesn't have a thermostat) when the fridge is full and I need to retard some dough.

Bread runs on its own schedule. A proofing box help it conform, to some extent, with yours.


awysocki's picture

Homemade Proofer for $44.61 using DIY store for supplies

February 28, 2011 - 3:50pm -- awysocki

Hi all, Living in the desert of Palm Springs where our humidity is usually around 15-20% I find it hard to keep my sourdough from drying out. I have tried the Oven, Microwave, box and so on and really haven't had the success I wanted.  So poking around TFL and the internet I found for under $50 I was able to roll my own.  I am pretty sure you can do it for less if you buy some of the supplies online.


alittlesquirrely's picture

Proofing box

February 10, 2011 - 1:54pm -- alittlesquirrely

I just discovered another use for a neck warmer. I lined a plastic tub with bubble wrap, heated the neck warmer 2 minutes in the microwave and placed it in the tub with the lid closed. Temperature went to 80 degrees within 2 minutes and stayed there for over an hour! It declined slowly and was still warm after 2 hours. In addition to heat, the warmer gave off moisture causing an almost steam bath in the tub! I used a "hot pockets" neck warmer. Carolynn

davidg618's picture

The microwave oven is a fine proofing box. With the door ajar, to keep the light on, its internal temperature is 78°F. Two small, round brotforms, or two oblong ones fit snuggly, but forget baguettes, or family size challah. And if I want 89°F I'm stymied--until now.

I've been working on a proofing box since late summer, but had to put it aside for a couple of months, due more pressing things. However, I finished it last week, tested it, made one modification and really finished this morning with the door pulls. Of course it still needs a coat of stain and varnish, or tung oil, but that's just for its looks. It's functional now.

I considered insulating it, but didn't think it necessary. It's heated by a 75 watt, halogen spot light, and the heated air is circulated by a small fan--normally used for cooling electronic devices.

The light's power is controlled by a plug-in thermostat, on the side of the box, through the power plug emerging from its case. The thermostat's temperature probe penetrates the side of the box, and monitors the return air temperature. With the box empty, the circulating air maintained temperature +/- 2°.  When the box contained three pounds of dough (two loaves) +/- 2°F remained the temperature range. The lower plug powers the fan, which circulates the air regardless of the heating light's power. The fan operates at USB low voltage, so I had to provide a 120 VAC to 5 VDC power supply, the small, black box partially hidden by the light's power cord. The box's top supporting the fan and light box, is removeable, and is replaced by a smooth top; it will serve as a storage box for banneton's and brotforms when not proofing.

The box can accomodate a variety of  proofing basket shapes and numbers, a half-sheet pan, and will be used to couche proof 20" baguettes, the maximum length my oven can accept.

The one modification I had to make was build and attach a diffuser to spread the air delivered by the fan; without it the interior box maintained too large a spatial temperature gradient.

My wife is delighted. Now she can reheat her coffee in the microwave without having to first remove proofing bread, and replace it following, which she's prone to forget.

I'm delighted because I can now proof all the differing shapes I push dough into.

Davd G

gringogigante's picture

Looking for a bread proofing box

December 29, 2010 - 4:50pm -- gringogigante

I'm looking for a bread proofing box for my sourdough starter. It's for home use, so I don't need/want an expensive commercial unit.

I searched for "proofing box" in the search field on the top, left. But, the only thing I saw were links to how to make your own.

I'm curious if anyone sells these.....


Chris McCollum

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