The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

How did you upgrade your proofing box?

Janet Yang's picture
Janet Yang

How did you upgrade your proofing box?

Assuming that you've experimented over the years, what do you consider the minimum practical size for a proofing box, and how do you provide controlled, even heat? Does your box use radiant heat or convection heat?


My proofing box is a styrofoam container for shipping medicine (thick-walled but small). I use a pet heating pad, and ambient temperature depends on how much of a crack I leave with the styrofoam lid! Since the pad is small, I need to rotate the bowl of dough periodically.

Time to upgrade. I don't want to use the heating pad this time because its temperature is not adjustable (and the cats have dibs on it in the winter).

cgmeyer2's picture

depending on how long you need to proof, if you have a microwave you can heat 2 cups (~500ml) water for 2 minutes and then place your dough to proof for up to 2 hours.

i think this might also work with an oven that is preheated on lowest setting. Place the water in the oven prior to heating. Turn the oven off after 2 minutes and place the dough in to rise.

hope this helps


Justanoldguy's picture

I use the oven for a proofing box. I generally bake sandwich loaves so after the dough is shaped and in the pan I pop it in the oven, bring a full tea kettle to a boil and pour the water into a large casserole placed on the oven shelf below the pan. That provides plenty of warm, moist heat for the proof. I don't have a cat so there is no prior claim on the oven, tea kettle or casserole. I may refill the casserole with boiling water after about an hour depending on what I've leavened the loaf with, yeast or sourdough.

HansB's picture

After trying several methods and contraptions I finally bought a real proofer. It sets up and folds together in less than 30 seconds, takes up very little room and maintains temp perfectly. It's not cheap I just wish I had bought it sooner!

Alan.H's picture

My proofing box was made several years ago from 10mm ply left over from a not very inspiring cupboard build. It was sized to comfortably hold a large plastic bowl for bulk fermentation or two smaller bowls lined with baking parchment for proofing. Heating is by a 40 watt incandescent bulb controlled by an old central heating wall thermometer. (I never throw anything away that "might come in useful"). Original insulation in winter time was a nice comfy blanket thrown over the box. It was very simple to build although it is necessary to be able to carry out simple electrical wiring safely or know someone who can help. More recently there have been upgrades to the insulation and the thermostatically controlled switch. It controls the temperature very steadily. I am away from home at the moment on holiday in Corfu but if it will be of any help I can enlarge on the above with pictures when I return next week. Alan

Janet Yang's picture
Janet Yang


Yes, please, I would like to see what you've done. Is the heat fairly even throughout? I was considering a tiny fan to blow the warm air around, although that might dry out the dough.

I never throw anything away that "might come in useful"

Me, too! My husband wishes I would throw it all away. Patience of a saint.


Dsr303's picture

im using a plastic box my bedspread came in. I put dough in and sit a cup of boiling water in there and zip it like a charm


Tom Hoffman's picture
Tom Hoffman

I recently have gotten interested in making sourdough no knead bread again afyrt no doing so for several years.  I needed a proofing box to control temp for a good even raise.  I decide to make mine using a Plastic Box I got from WalMart approx "16LX9"WX9"D,  I set this on a plant flat heat mat using a digital thermostat control which both the mat and control are available from Amazon.  It gives you great control and predictability somewhat.  It will keep even temp indefinitely, you can add water to the inside of the box for humidity if you want.  I do all the steps using the box and the final rise in the pan in the box too.  I have a round aluminum 3" deep pan for the final rise vessel. I heat my round 9" dutch oven, take the risen bread loaf and put pan and all in my Hot Dutch Oven and bake like normal.  Seems to give a nice finished deep loaf.

Alan.H's picture

Back to England now, enjoying some grey skies and cooling light rain in Norfolk after the blue skies and sunshine of Corfu!    Oh well!

Anyway I can now add to the basic details of my last contribution about my proofing box and its upgrades.

Interior dimensions are width 17" (43cm). Depth 14.75in. (37.5cm)  Height  9.25in. (23.5cm)

 Here it is in its current incarnation. 


It started off as a plain wooden box with hinged lid and as mentioned before a 40 watt bulb controlled by an old central heating wall thermostat.  The first upgrade was the addition of the glass window after I had come across the 4 mirror corner supports in one of the many tin boxes I have for keeping "useful things" in which had lost its label.  The window is very convenient for checking the condition of the ferment/proof and internal temperature without opening the lid and losing heat.

Next upgrade was the change to a digital temperature controller when the old mechanical one siezed up and became very difficult to adjust. It must have been decades old by then and had served very well so was retired with honour.  This one is a cheap chinese module which I bought through ebay after seeing a favourable review in a you tube video.


It is very easy to use an seems to maintain a very constant temperature. The central red figures show the temperature inside the box which is measured by the sensor probe hanging down in the box. the smaller yellow numbers on the left can be set to a degree or two lower than the desired proofing temp. and the right hand numbers to a degree or two higher and as the interior temperature moves between the two, the bulb or heater is switched on and off.

The last upgrade came after we had a leaky roof fixed and the loft insulation improved with foil covered insulation panels and there were some spare pieces left over. So here is the proofer in his winter coat and the comfy blanket has been retired.

As to your later question about whether the heating is even, there are differences of a degree or so within the box (I've tried to measure with various thermometer placings) but I reckon that there will be sufficient convection movement to keep it all pretty even. I always keep my fermenting and proofing dough covered with a plastic shower cap so there is no problem about drying out.



Janet Yang's picture
Janet Yang

Alan, what will you use for heat, when 40-watt incandescent bulbs are discontinued?

Alan.H's picture

Janet, you've discovered the elephant in my room. Yes incandescents are being phased out worldwide because they are so darned inefficient as light sources which is what makes them so useful as economical heat sources.

However 40w and 60w incandescents are still available on Amazon and Ebay and a few low cost high street shops so anyone who wants to put a few aside will be able to proof for quite a while yet. I have half a dozen which at my age will probably outlast all my future baking expectations.

Beyond that all is not lost. I have searched under the general description of enclosure heaters or cabinet heaters where there is a variety of low wattage and relatively inexpensive heaters and anti condensation heaters which could be adapted for heating a proofing box, so even if I did outlive my hoard of light bulbs there will be a solution.



gerhard's picture

There are heater elements that screw into a standard bulb socket, designed to main terrariums toasty warm for whatever cold blooded creature you want to keep happy.  So check out a pet store or two and you will find the heaters,  good thing is they work with light dimmers.