The Florence Siphon
From MAKE MagazineThis project first appeared on the pages of MAKE magazine.
Make your own mad-scientist coffee machine.
- Author: John Edgar Park
- Difficulty: Moderate
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- Drill, or stopper borer to create a 4mm hole
- Gloves, thick, leather for heating and bending glass
- Safety goggles
Relevant parts (continued)
- Connection tubing, latex, 2" length
- Thistle tube, Latex connection tubing, 2" length
- Filter, cloth I used a Yama vacuum pot filter from http://sweetmarias.com/prod.brewers.vacuum.shtml.
- Rod stands (2)
- Clamp, four-fingered for Florence flask
- Tube clamps (2)
- Burner, butane
- Stopwatch, or other timer
- Grease pencil, or crayon
- Tongs, flask (optional)
- Flask stand, cork (optional)
- Pouring funnel, (optional)
Edit Step 1 — Build it.
- I purchased all the lab supplies from Avogadro’s Lab Supply (http://avogadroslabsupply.com).
- Use only brand-new lab equipment. Used glass can contain seriously scary things that can kill you.
- Wash the glassware with a small amount of dish soap and warm water.
- Assemble your stands and clamps as shown in the photo. Put the burner, Florence flask, and Griffin beaker in place. To connect the 2 vessels, you’ll need to put two 90° bends in the glass tubing.
- Measure the height of your Florence flask, then add 3". This is the length from one end of your glass tubing to the first bend. Place a mark there with a grease pencil or crayon. Measure the distance between your tubing clamps. This will be the distance between the two 90° bends. Mark this distance from the first bend on the tubing.
- Turn your butane burner on high heat, don your gloves (or optional mad scientist gauntlets), then place the glass rod at the first bend mark. Roll the tube in the flame, putting gentle pressure on it so you can tell when it begins to soften. When it’s soft enough, gently bend it to 90°. I’d never done this before this project, and it sure is fun!
- Wear thick leather gloves and long sleeves when bending or inserting glass tubing.
Edit Step 2
- Using the same method, bend the glass tubing at the second mark. It’s important that the bends are aligned on the same plane, so you may need to reheat and adjust.
- You should also heat the ends of the tube and roll them in the flame to round off the sharp tube edges. Don’t overheat them and close off the ends!
- Using either a drill bit or a stopper boring tool, make a 4mm hole through the center of the rubber stopper. Lubricate the hole with glycerin and very carefully push the long end of the glass tube into the top of the stopper hole. This can be dangerous if done too quickly, so take your time, think happy thoughts, and wear gloves and long sleeves. The stopper should hold the glass tube about ½" off the bottom of the Florence flask when properly seated.
- Cut a 2" length of latex tubing, and use it to couple the glass tubing and the thistle tube.
- Place the cloth filter over the end of the thistle tube’s funnel mouth, then pull the drawstring tight and tie it off. (I had also inserted a Teflon screen that proved unnecessary.)
- Attach the filter/tube assembly to the 2 tube clamps, so that they hover above the Florence flask and Griffin beaker. You should test pushing the assembly down so that the stopper is in place and the filter rests about 1" above the beaker floor.
- You can adjust these heights with a greater length of latex tubing, or use a stand to prop up the beaker, as I did. I found a disused wine bottle holder that did the job nicely.
Edit Step 3 — Brew it.
- Preheated water can be a timesaver. Raise the filter/tube assembly, then pour 500ml of hot water into the Florence flask.
- Grind fresh coffee beans on a medium-fine setting, somewhere between a drip and an espresso. You’ll fine-tune this over time. Pour the grounds into the Griffin beaker.
- Lower the filter/tube assembly until the rubber stopper is firmly in place. The stopper must have a good seal all the way around. The filter end will be dug down into the grounds at this point.
- Don your safety goggles, then ignite the burner. It should take a few minutes for a butane burner to bring the water up to temperature. Watch for the water to rise up the tube, defying gravity. It’s a very exciting moment!
- Once nearly all of the water is in the Griffin beaker, start your timer. Lower the heat enough to maintain a low, bubbling roil in the small bit of water that remains behind in the Florence flask. This will keep things from progressing too quickly.
- Give the water-saturated grounds a few stirs with a spoon or rod. If your coffee is fresh you’ll see it “bloom” as gases are released.
Edit Step 4
- After 1½ minutes have passed (you’ll learn to adjust this timing, so keep notes), turn off the burner and remove it.
- As the flask cools, steam will contract and draw the coffee out of the grounds and back to the flask.
- When the coffee has stopped flowing, carefully unstopper the flask and raise the filter assembly tube. Remove the flask of coffee.
- Pour yourself a cup of the most delicate, nuanced coffee you’ve ever brewed. Drink and enjoy madly.