I’m sure you’ve heard of tamping coffee before. If you have heard of it and don’t know why we do it or if you haven’t heard of tamping coffee before and are wondering why we do it. This post should answer any questions about tamping coffee and the reasons we do it backed by a little bit of physics.
So if you’re tamping your grounds that means you are preparing your coffee for an espresso shot. That requires the grounds to be put under pressure. That pressure is a result of the water being forced out of the machine and the resistance that the compacted coffee is giving back to the water.
Why We Tamp Our Coffee
When the grounds are placed in your portafilter they are very loose and unevenly distributed .
Note: A portafilter is the part of the coffee machine that holds your grounds and basket. It attaches to the espresso machine.
We tamp the grounds to make an evenly distributed, tightly compact puck of coffee so that we can get the perfect amount of pressure and water distribution to get full extraction of the coffee grounds.
Tamping coffee really is simple; Apply flat, even pressure to your perfectly dosed coffee grounds.
The reason we tamp our coffee grounds is dictated by simple physics. Water will go to the path of least resistance.
A good tamp will direct the water evenly over the entire puck of coffee. A bad tamping will allow water to flow unevenly, through loose pockets of coffee. That means that there will be some grounds that are getting over extracted and others that are getting under extracted.
Tamping Coffee: How To Do It Properly
Getting good at tamping coffee may take you a few tries, but I know that anybody can get a barista champion quality tamp.
First things first. Once your grounds have been dosed into your portafilter they will be piled in there very unevenly. You want to try and distribute those grounds as evenly as you can using your hands. There is a technique called the Stockfleth’s move if you want to get fancy but you can get good results by just using your finger to ensure the grounds are as level and evenly distributed as possible.
The next thing to remember is that there is no need to go super hulk when trying to tamp your coffee grounds. All of that extra force that you exerting isn’t giving you a better tamp. It’s only risking injury(If you’re doing it all day) and in all actuality probably giving you a worse tamp.
Lots of people will tell you that 30 pounds of pressure will give you the ideal amount of force to get the perfect tamp. However, there are also a lot more people that will tell you the amount of pressure you apply when tamping isn’t as important as being consistent is.
I agree with the later, as long as you are consistent every time you tamp it will be easier for you to get the feel of what a good amount of pressure will feel like. Also, since you’re not applying the max amount of pressure that you possibly can it will be easier for you to fine tune and make any adjustments you need to make in order to get an even amount of pressure distributed throughout.
As soon as the tamper will no longer move and you feel the coffee grounds pushing back I would say that you have applied enough pressure.
Something that I found very interesting is that no matter how much force you apply to the top of the coffee grounds, in the bottom ¼ of the basket there is almost no compaction occurring.
This was actually found by mistake, when the company La Marzocco was developing a machine called the swift, that would automate the process of grinding and tamping. They were developing this machine in order to help out starbucks. This was going to reduce training time and provide consistent results time and time again.
As the machine ground the coffee it applied even, constant pressure at 30 pounds as the grounds were being added to the basket. The end result was that the coffee was so compact that water couldn’t even pass through. They ended up designing the machine to apply 8 pounds of consistent pressure.
So I hope this proves to you that there is no need to push your hardest when tamping coffee.
Now that we know we don’t have to be the hulk and that we should be consistent every time we apply pressure when tamping, the next thing to know in order to get a good tamp is to make sure when you are applying pressure that your tamp is perfectly flat and even. You want the coffee puck to be as level as possible.
The best way to do this is through proper ergonomics. You want to hold the tamp in your hand comfortably, kind of like if you were grabbing a doorknob.
Chris Baca has some great tips on tamping coffee and one of them is to pay attention to your body position. Whatever hand the tamper is , you want that side of your hips up against the counter with your elbow straight up in the air, directly above the portafilter.
For instance, if the tamper is in your right hand, place the right side of your hips up against the counter.
This body position allows you to apply a straight line of force directly down onto the coffee grounds. If your elbow or wrist is bent off to the side you can put unnecessary pressure on your joints and you will have more of a tendency to come at the grounds sideways giving you an uneven tamp.
Remember, no need to rush, take your time. Before placing your tamper onto your coffee grounds, let it hover right above them and inspect that you are about to apply pressure straight down onto the grounds.
A good way to check the levelness of your tamp is by leaving the tamper in the portafilter and pulling them both up to eye level. Is the tamper sitting flat or is it leaning to one side? If not, that’s alright there is a little learning curve. If it’s not perfectly flat don’t bother trying to fix it, you won’t be able to. If you go back and try to apply more pressure you may actually break your puck of coffee. This will give you a worse shot of espresso than a slightly uneven tamp will. Remember, water flows to the point of least resistance and a crack will be an easy path for the water to flow through.
After you have applied a good amount of pressure straight down on your grounds the next big step is to remove your tamper slowly. Again, no need to rush this step either. According to Gwilym Davies who was the 2009 barista world champion, If you remove the tamper too quickly you may cause some suction and that may lift your coffee puck a little, disturbing your grounds.
You may have heard of some people that give the tamper a little twist as they remove it. Gwilym Davies says that he does it but he admits that it provides no real benefit. If I were you I would stray away from giving the tamper a little twist as removing it just because that is another way of disturbing your perfectly compressed coffee grounds.
There are all sorts of different tampers out there to buy. Some have curved bottoms, some have crazy handles and some are made out of fancy materials. Really all you’re looking for in a good tamper is one with a flat bottom and that fits comfortably in your hand.
Note: be sure to take a look at your machine’s instructions, that should tell you the size of your tamper. You want a tamper that is ever so slightly smaller than the diameter of your filter basket.
And that’s all there is to tamping. There is no need to over complicate the process.
Tamping really isn’t that hard but it is an important step to achieving a great shot of espresso. So remember, to get a good tamp on your coffee you don’t need to worry about how much pressure you have applied but that you are doing it in a consistent even manner. Coming straight down with your tamp, not at a wonky angle and removing the tamper slowly. These simple steps will give you a good tamp and ultimately a better shot of espresso.
If you found this article helpful give it a share on facebook or twitter and join in on the conversations!