The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Looking for a bread proofing box

gringogigante's picture

Looking for a bread proofing box

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

Caltrain's picture

What requirements for the proofing box are you looking for?

In most cases make-shift methods work perfectly for home purposes. Any insulated box, such as picnic coolers, with some low heat source, such as a heating pad or jars of hot water, will work perfectly.

If you need to monitor temperature, take a cheap styrofoam cooler and stick a meat thermometer through it. I've been doing this and it works great.

Hope this helps.

gringogigante's picture

Haha....well, i'm pretty new to all this. I jsut got a starter in the mail, and the book says that I need a proofing box. I'm new to sourdough, so I guess I'll just make a small one my self.

In the past, I've just stuck the dough in a microwave with a cup of hot water. But, I understand that sourdoughs need a much longer time for proofing. So, a cup of water in a microwave may not last that long....

what are your thoughts?


K.C.'s picture

Instead of a cup of water use a thermos bottle filled with boiling water. Refresh it every few hours as the humidity drops. 

You can also just try working without a proofing box/case. Many bakeries do and they produce wonderful bread that fermented and proofed at room temp. As seasons change room temp along with them you simply learn to adjust the times needed for each step.

Janknitz's picture

I've found that a pyrex measuring cup full of just boiled water will keep the microwave warm for at least 8 hours.  I just reheat the water every time we need the mircrowave. 

I put my instant read thermometer in the microwave so I can see at a glance what the temperature is in there. 

Works great!

Nickisafoodie's picture

using your oven with just the light bulb on gives a nice 77-79 degree temp, perfect for those little cells to multiply!

davidg618's picture

Prop the door open--only enough to keep the light on--and check the internal temperature before you put your new starter in to it. The best information I've found on the internet shows that sourdough lactobacteria will grow at tempertures from 40°F to 90°F, their rate-of-growth increasing with the temperature. Above 90°F growth rate drops off quickly.

Yeast grows between 40°F and 82°F also increasing rate-of-growth with temperature, and falling quickly above 82°F.

The data I've looked at was for two specific lactobateria strains and one specific yeast strain, but its safe to assume most (probably all) sourdough bacteria and yeast will propogate in these same ranges.

I routinely build levain, and proof sourdough loaves in my microwave oven, with the door proped ajar. My levain builds peak in 6 to 7 hours, and loaves proof in 1 to 1-1/2 hours. The internal temperature runs about 78°F.

I use Sourdough International's Ischia Island starter, which I initiated using my microwave oven. I successfully baked with it four days after starting. I'm still using it nine months later, and it is wonderfully reliable.

Welcome to the wonderful world of sourdough baking

David G


rincewind03060's picture

I just made a proofing box from a sheet of 1" x 24" x 8' foam insulation I bought at Lowes. I cut it up and used duct tape to hold it together while I ran a bead of silicone caulk around the inside joints.The inside dimensions are 16" x 22" x 12" deep.

I have proofed a couple of loaves so far and it works great with just a 2 cup pyrex measuring cup full of boiling water stuck in a corner.

Once in a while I check the surface temperature with my handy Harbor Freight infrared thermometer and replace the water if necessary. Actually, the danger is of overheating more than being too cold. 1" of foam is a really good insulator.

So I combined my two favorite things "Simple" and "Cheap". Now where do I store it?


pjkobulnicky's picture

You didn't say where you live (is it warm or cold outside) or at what temprature you keep your house.  If you keep the house somewhere near 70 F then you do not need a proof box. Otherwise, the hot water in the oven trick (or the light on if it is a halogen or incandescent light bulb) will work just fine.

TimandGlendaG's picture

Would an insulated ice chest (like you would use for a picnic) work well?

davidg618's picture

And the inexpensive foam ones will be just as good (if not better) than the thirty-dollar adult pull toys.

David G