You don't have to be a guild-certified, Level 40 barista to know that paper filters and metal mesh filters are fairly different beasts.
Fine, maybe they aren't "beasts." But they are different.
Reusable coffee filters are typically made of metal mesh, and they're designed to be used over and over again. In fact, most coffee drinkers would probably say "the entire point" of a reusable coffee filter is that you can use it without having to bring paper into the equation at all.
On the other hand, paper coffee filters are designed to be used once and then thrown away. You don't have to worry about washing (and drying) them after each use, and you don't have to worry about storing them in some awkward spot in the cabinet until you need them again.
This is probably their biggest advantage: they're extremely convenient. Except when you run out of them. Then they're the opposite of convenient.
But what about when you're using a reusable coffee filter?
Is there some advantage to using paper filters in tandem with your metal mesh filter?
Or was this entire affair just an excuse for me to use the phrase "in tandem" in a sentence?
Let's find out.
The Pros of Using Paper Filters with a Reusable Filter
1. They Can Help Make Your Coffee Taste "Cleaner"
No matter how well you clean your reusable metal coffee filter, there's usually still the potential for some residual oils and coffee grounds to end up in your cup. It really depends on the size of the openings in the mesh—but in general, your average metal filter isn't going to do as good of a job at keeping things out as a paper filter will.
Note: Higher-end reusable metal filters, like this one from Espro, have a micro-mesh pattern that does a much better job of keeping things out of your brew.
Paper filters can help to reduce the amount of oils and coffee grounds that end up in your cup, by acting as an additional barrier between your coffee and the metal mesh of the reusable filter.
This means your coffee will look and taste cleaner. This is especially important if you're using a light roast, which has more oils that can seep through a metal filter compared to a nice, strong dark roast.
Note: See the “Cons” section further down this page for the flip-side of a cleaner brew.
2. They Can Lower the Cholesterol That Ends Up in Your Cup
Along with all those great-tasting, caffeine-loaded solubles, coffee beans also contain cafestol. It’s a type of diterpene that has been shown to raise levels of cholesterol in some studies. (Cafe-stol is also a really adorable name for a cholesterol molecule in coffee, if you ask me.)
Anyway, cafestol is more likely to end up in your cup when you're using a standard metal mesh filter, because it can seep right through the openings in the mesh. This is why people sometimes say that espresso raises cholesterol, because of the lack of a paper filter in the machine. Paper filters, on the other hand, do a pretty good job of catching cafestol and keeping it out of your cup.
Some cholesterol in your coffee isn't necessarily the end of the world (put the phone down) but if you're trying to avoid it for health reasons, paper filters can help.
3. They Can Prevent Your Coffee from Tasting "Muddy"
When coffee grounds are left in the brew for too long, they can start to break down and release more bitterness into the cup. This is why it's important to brew with fresh grounds, and to use a coffee filter that will catch all the grounds and prevent them from over-extracting.
Paper filters are generally better at doing this than metal mesh filters, because they have smaller openings that coffee grounds can't slip through as easily. This means your coffee is less likely to taste "muddy" or overly bitter.
Cons of Using Paper Filters with Reusable Mesh Filters
1. It's Definitely Not as Good for the Environment
One of the points of using a reusable coffee filter is to be less wasteful and more environmentally-friendly, right? Well, using paper filters every time you use your reusable filter sort of defeats the purpose of that.
2. It Can Take Longer for Your Coffee to Filter Through
When you use a paper filter in your reusable coffee filter, it can take longer for the coffee to filter through. This is because the paper filter acts as an additional barrier that the coffee has to seep through, on top of the metal mesh of the reusable filter.
You can imagine how this could also make your coffee taste stronger, more bitter, or just generally different since the water is in contact with the grounds for more time.
3. A Cleaner Brew Can Equal Less a “Full-Bodied” Coffee Experience
If you're used to the taste of coffee that's been brewed with a metal mesh filter, adding a paper filter might make the coffee a little bit "cleaner." This isn't necessarily a bad thing at all, but it can be a bit of an adjustment if you're used to the “mouthfeel” of coffee that's been brewed without a paper filter.
Paper filters can make coffee taste less full-bodied, because they can filter out some of the oils and coffee grounds that contribute to that richness. However, this might not be a bad thing if you're trying to avoid too much cholesterol or bitterness in your cup.
Conclusion
So, should you be using paper coffee filters together with your metal reusable filter? Well, there are pros and cons either way.
In the end it comes down to your personal preferences, and how you prefer to brew your coffee.
It's important to note that a lot of coffee brewers won't do well with the whole "two filter" deal, so you only want to try this with a manual pour over or similar brew method. Definitely don’t try doubling up in your Keurig or in your basic auto-drip machine.
Also: If your coffee is already on the “super strong” side, you might not want to use a paper filter and make it even “super stronger”—on the other hand, if you want to make the strongest coffee possible, adding another filter layer couldn't hurt.
Lastly, if you're someone who is looking for the absolute cleanest cup of coffee possible, or is just trying to avoid raising their cholesterol at all, then using a paper filter in your reusable coffee filter is probably the way to go.
But if you're trying to be more environmentally friendly, or just don't like the idea of using paper filters, you can definitely skip them.
Just don't skip using a coffee filter altogether, because that's gross.
(Unless you're making cowboy coffee. In which case, giddy up.)
