The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

My "homemade" proofer box

sam's picture

My "homemade" proofer box

Hello there!

Here is my homemade proofer box.  A simple plastic box, fed by a soft flow of warmed humid air from a spare CPAP machine and humidifier I had in the closet.   It works!

Upon initial power on:


About 15 mins later, the thermometer inside registers 84F, still climbing.  I have yet to see how warm it will go.   Then I will play with the knobs to dial it into a 78-80F range.

Here is another shot with the flash turned on, it shows the reflection of the condensation which has formed on the inside of the box..  so there is definitely humidity.  :)




 Editing to add:   After another 30 mins, temperature appears to have maxed out at 84F.   That should be plenty high for any kind of dough.  From what I read in Hamelman's book, for the majority of white / wheat breads you don't want to ferment higher than 80F.


Mebake's picture

Ingenuity, gvz! what a nice contraption!

This is great for final proofing.. What about initial proofing?


dwcoleman's picture

Great idea, I have a spare CPAP with humidifier laying around too!

sam's picture

Thanks Mebake!

I suppose it should work fine for bulk fermentations also, ideally in combination with getting the desired dough temperature correct to begin with during mixing, so the box will keep the dough at a good temperature without needing to cover in plastic. (Not that covering dough in plastic is any major hassle, but it is nice for the surrounding air to be humidified anyway.)  Or, it could be a good box for raising the temp of a refrigerated dough.

From a cold-start, the box takes about 10-15 mins to achieve its full warmth (the heater plates from the humidifiers take a little time).  Once the box is warm+humid, it is easy to keep that way.  If I am careful, opening + closing the box to add/remove items doesn't cause much of the warm air to escape.

To get temps above 78F, I had to hook up two humidifiers (one that is built into the CPAP machine itself, and an additional one I had spare as well).  The picture above shows both connected.  With a single humidifier, I could get 77-78F.   Adding the 2nd humidifier can provide me up to 84F, if I wanted to max it out.   Playing with the knobs on both humidifiers, I dialed it into a perfect 80F.  Also, I set the CPAP machine air flow/pressure level to the lowest -- 4cm -- so it is a very gentle air stream.  One last bonus is:  The air is filtered, so no dust or yucky stuff blowing around my dough babies.  :)  Will be trying it out for real with some dough soon!

naschol's picture

I would be interested to know if this has any affect on the crust.  Is it thicker than usual?  Thinner?


Any differences you note would be interesting!  I may have to try this, as well.

sam's picture

Will do.   A few weeks back, I googled around and found various restaurant /  bakery-style dough proofer/warmer racks.  The nicer ones had a digital thermometer readout + control to set the temp, but I did not see any that would let you dial in a specific value for absolute or relative humidity.  Of course, depending on temperature, air can only achieve so much humidity.  The professional proofer racks' humidity controls appeared to be a simple a knob you'd turn to raise or lower humidity.  Some had a pan (for water) at the bottom of the rack with a heater plate, others had an intake receptacle in the front to pour water in.   So, my CPAP machine method is the best I can do with spare equipment on hand...   and I'm not willing to pay a thousand dollars or more for a professional thing, and wheel-in a big proofer rack into my garage or house.  (Although they do make+sell smaller half-size units, but still expensive).  On the other hand, CPAP machines can also be expensive, but since I already had one available... 


fminparis's picture

Makes you wonder what bakers did 50 or 100 years ago. I was in Lionel Poilane's bakery in Paris and never saw one of these. 

fminparis's picture


So how do I delete a post?  I must have clicked twice on "Submit" and got two identical posts. How do I delete one?  I edited one to write this.


sam's picture

You are right, fminparis.  If Poilane in Paris does not have one, I shall not either.  Back to the closet for that CPAP machine.  I hope it is acceptable to use the plastic box for storing paperwork items (its original intent from the office supply store).  I don't know how people 100 years ago kept their papers, did they have plastic boxes back then?  :)   I need to learn woodworking.

flodnar's picture

Best and cheapest method is still the Oven. Trun on for 1 minute, then off. Turn on the Oven light. Proof away. No additional room or cost involved.

JoeV's picture

Back when I started baking bread and thought I had to do everything like they do in a bakery to achieve decent results (I think differently today), I used to boil a coffee cup of water in the microwave, then place it in the corner with the dough in the middle of the micro. What did I gain? I gained a faster rise to my dough, which is exactly what the bakery wants. Faster rise times means the product reaches the customer faster, and requires less labor time which means money is saved and profits are increased. Today, I know that longer rise times add flavor to the bread, and my dough sits on the counter, regardless of temperature in the kitchen, until I see that it is time to shape the loaves for their second rise. Second rise is the same....I watch the dough untili see that it is time to pop in the oven. For exceptional flavor I do an overnight cold proof in the fridge.

There is nothing wrong with creating a warm, moist environment for your bread dough, especially if your time is limited for baking. But be aware that slower, cooler rises will impart another level of flavor to your bread that you won't get with fast rises.

deweytc's picture

I use a large plastic box (upside down), that I can get six 1 lb loaves in.  I place a small custard cup, on a folded-up face cloth, on the lid, in the middle and then pour boiling water into it.  It steams really well.  I may repeat this every 20-30 minutes for at least 3 times.  It keeps the dough well moisten.  I know that I have shorten my final rise time by at least an hour.  I have not check the temp, but will do so and report back.

sam's picture

Well, that was a complete failure.  :)

I finally got to trying my warmed/humid box.  Yesterday I began by preparing a biga and soaker, both each at 80% hydration.  I had them in the fridge for about 24 hours.  The plan was to combine the two, and add the required amount of additional flour to arrive at a final 68% hydration dough.  I have done this before without issue.

This time, I took the biga + soaker out of the fridge, took off their lids (they were in small plastic buckets), and put them in the warm/humid box (minus lids).  I took the lids off so that the contents would be exposed directly to the warm air.  My hope was that the humidity would keep them from drying while they warmed up.

Bad idea.   They took on way, way too much water from the humidity.  The final dough felt and handled more like an 85% hydration dough, or something like that -- extremely sticky, tacky.  After many stretches+folds, it would strengthen a lot and become more workable, but if left to rest, quickly slackened, difficult to hold much shape.

Well, with a significant amount of flour on the workboard, I managed to shape them into something resembling baguettes, and put them into perforated baguette pans.  These would easily flatten out if I didn't have in pans.  Maybe I should have turned it into ciabatta or something.

On the final rise now, NOT in the humid box, of course.  :)   I'm not expecting much, but will bake 'em anyway. 

Live and learn!   It was still fun to try.   :)

Editing to add/clarify:   With that CPAP-infused warm air, to get up to 78-80F temp, the amount of humidity is...  you can run your finger alongside any container inside of it, and pick up enough water to have a little sip.  :)  It is truly excessive.

Janetcook's picture

We must have been doing this on the same day!  My set up was a bit different but I had read this thread BEFORE you used it on the 4th....

I placed 2 mugs of boiling water in my plastic box and then placed the loaves on the floor of the box.  The lid was snapped into place and the moisture began to condense on the walls of the box.  I had a couple of errands to run so I took the mugs out of the box but left the dough where it was....bad idea.

I came back 45 minutes later to 2 very flat loaves staring up at me as though pleading to be saved from their rain forest like environment....

Like you it was a good experiment in that I will not forget what happened for awhile....If I have to use the box in the future for warmth with refrigerated doughs that I want to warm up quickly due to time constraints I will be sure to pop the loaves into my good old plastic bags so they can get the warmth without the moisture.

Onward to the next bread experiment....I have them lined up like my list of loaves to bake.  :-)

Wild-Yeast's picture

Hi gvz,

I don't think your proofer box is a failure.  At least you know why it failed.  

I think the setup to be novel and inventive. Just needs a little adjustment...,  

Dust the dough with little rice flower and put the bannetons inside plastic bags making sure to fold the loose end underneath the baskets before powering on.  


nowhereman's picture

Thats a fairly ingenious design, hope it works properly and you get good results



sujoy's picture

Plastik box  Am häufigsten werden stapelbare Plastikbox eingesetzt. Ihr Vorteil: einfaches Stapeln mit minimaler Anstrengung.