Introduction: ALCHEMA (or Any Fermenter) Brew(d) Box

About the device

The silver egg you see here is an ALCHEMA, a new device for brewing short runs (81 ounces) of cider, mead, and wine. Thanks to a sensor system and scale built in this egg, ALCHEMA keeps you informed via smartphone or tablet of alcohol content, temperature, Brix level, and time remaining before the batch is ready for chilling and serving. Slick, right?

Indeed it is, but certain factors are beyond the ALCHEMA's control.

The problem: Temperature vs. time

When I ran my first batch of cider, I placed the ALCHEMA on my desk in my command cent - uh, basement office, where the temperature lies between 63°F and 65°F. Original estimated fermentation time was four days. Within 18 hours of starting the run, the total time for my batch increased to 24 days. Then 25. Then 26.

In the name of total disclosure, I've done quite a bit of beer and mead brewing in the past, and never have I had a four-day ferment on any of my brews.

On re-reading the recipe, I noticed that the manufacturer listed the ideal temperature range as 57-75°F, with the original proof-of-concept recipe made at 82°F. Most buildings aren’t kept at that temperature, unless the building is a plastic extrusion facility. Nevertheless, my 65°F basement was going to make for a long, slow ferment.

A temporary solution

The short term goal was to raise the temperature slightly, to yield a shorter fermentation period. For this first batch I dug out a light source, bought in celebration of earning my multi-engine pilot certificate ($0.50 at a yard sale) to help the fermentation along. I also left the ALCHEMA access door open - not ideal, but it won't really hurt anything. (Lifting the top lid during fermentation, on the other hand, not a good idea.)

For the last two days of brewing, I decided to experiment a bit more: A found cardboard box, some bubble wrap to hold in the warmth, and a clamp-on work light. This configuration held the unit at around 73°F, which appeared ideal for this recipe.

A longer term solution

While the heat source helped, it lacked elegance. Besides, I wanted a solution that could work unsupervised.

Since yeasts are a single-celled fungus, maybe we can look to hobbies other than brewing - gardening, raising chickens - to create a solution that will keep the temperature friendly toward yeast and optimize our brewing time. Hence the name Brew(d) Box, along the lines of a brooder for chicks.

So, I needed an enclosure and a heat source. Direct heat might do bad things to the ALCHEMA, but some ambient warmth would help the fermentation process.

We have an enclosure: The aforementioned cardboard box.

When I had time to brew five-gallon batches regularly, I would place a heating pad set on low under the crock or glass jug to ensure a nice environment for the yeast beasts.

If you don't own an ALCHEMA, that's okay. It's an interesting piece of tech, but if you're a home brewer who wants to regulate a batch's temperature, this should work for you as well. Read on....

Step 1: Get Stuff!

You will need the following items, many of which can be found items, and you can probably find others at your local dollar / pound / 100 yen store:

  • corrugated box larger than the ALCHEMA
  • packaging tape
  • heating pad
  • Two tea towels, pot holders, or silicone trivets (mix and match)
  • cooling rack
  • bubble wrap or other insulation (optional)
  • plastic sheeting


Select a heating pad that does not shut off after a period of time. Many modern pads have this as a safety feature. Look in thrift stores, or buy a pad for gardening purposes (for keeping germinating seedlings warm).

I used a tea towel because it was available, and a knitted pad. If you have a large pot holder or other item, feel free.

Avoid the cheapest, most easily torn plastic sheeting. A low-priced dropcloth will do, or even some bubble wrap.

Step 2: Prepare the Box

If your selected box is larger than the ALCHEMA, the most you may have to do is cut off the tabs, leaving one side open for application of plastic sheeting.

Since the cats have taken over the original shipping box (see illustration), and the ALCHEMA carton itself was too small for this purpose, I was forced to look elsewhere. I found something around the house that wasn't quite the right depth. So, I taped the tabs together using packaging tape to form an open box.

NOTE: At this point, you may want to glue or tape insulating material to the interior of the box, whether you use bubble wrap as suggested, more corrugated cardboard, or foam insulation. Remember the goal is just to maintain a temperature, not overheat the wort / must / whatever you're making, so you may or may not need this step. I found the enclosure itself was enough. Your mileage may vary.

Cut a small flap and notch in the rear of the box to allow you to run the USB cable, and the heating unit's power cord, out of the box to a nearby USB power supply and electrical outlet.

Place the heating pad in the bottom of the box, and run its power cable out the hole you cut in back. Run the USB cable out of the box through the same hole.

Place a folded tea towel, large pot holder, or silicone sheet trivet on top of the heating pad. This protects the heating pad from the cooling rack feet, and keeps the cooling rack from acting as a heat sink to the ALCHEMA unit.

Place the cooling rack on top of the towel / pot holder / trivet.

Place the second tea towel etc. on top of the cooling rack. This minimizes heat conduction through the cooling rack to the base of the ALCHEMA.

Cut plastic sheeting to a size larger than the open end of the box, and tape the sheet to the top of the open end only (what will be the top end when the ALCHEMA is inside).

I used plastic sheeting, rather than a cardboard "door," for visibility. There is an LED display on top of the ALCHEMA that shows status, be it white (fermentation), yellow (almost done fermenting), or red (the dreaded red ring of death, which means the batch has gone bad). I wanted to see that status ring, as well as the Wifi indicator, hence the clear plastic.

Step 3: Add Your Boozinator

Place the ALCHEMA unit on top of the towel/pad atop the cooling rack. Ensure the ALCHEMA is stable.

Connect the USB power supply. Plug the USB power supply into an electrical outlet.

Turn on the heating pad and let the box preheat. While you're waiting, make a batch of something.

Install the pitcher, and start your batch running.

Step 4: Temperature, Tweaking, and Beautification

The ALCHEMA unit monitors temperature, and sends that data to its proprietary app, available for iOS or Android. While I was experimenting with this project, I would open the ALCHEMA door and take a temperature reading using an infrared thermometer (available at your local hardware store), to ensure even warmth.

My goal was to keep the fermentation temperature steady at 73°F-75°F, and I met that goal. I found that if I'd used ingredients right out of the refrigerator, fermentation started slowly -- my error. Again, all we want to do is keep the unit warmer than the surrounding space by a few degrees. Another factor to consider is the ALCHEMA unit itself, which generates its own warmth, and you may end up cutting louvers in the box to ventilate, or removing the plastic altogether.

As for additional insulation, I needed none. The cardboard box contained the warmthnicely. Again, your mileage may vary.

But it's so ugly! Make it nice!

Yes, I know. No, I won't. My intent was to design a simple proof-of-concept box that anyone could put together with easily found stuff, following the tenets of that greatly underrated homebrew instructor, John F. Adams. Go thy way, build thine own, decorate it to thy heart's content.

By the way, if you can find a copy of John F. Adams' An Essay on Brewing, Vintage and Distillation, Together with Selected Remedies for Hangover Melancholia, Or How to Make Booze, and the seller is asking a reasonable price, buy it. Read it. The beer and mead chapters are pure gold.


Disclaimer: The writer of this Instructable is not an employee of ALCHEMA, nor is he endorsing or recommending said product in any way. If you are a home brewer with the basic tools, this project may still be of use to you. Nor do I have copies of Adams' book for sale. Not responsible for mead or cider hangovers from use of this box or fermenter.