FAQs and tips

Rumble Jar brewing questions

I lost the instructions for brewing with a Rumble Jar. Can you help?

Sure can! Here's a link to a copy of those simple instructions we included with your Rumble Jar. Feel free to print it out a thousand times to make some avant garde wallpaper.

Those instructions are too #basic. Can you give me more details please?

Sure can! Right here: detailed instructions

Can I shake it a lot? Like, waaaayy more than a few Rumbles?

You can do whatever you like, but we wouldn't recommend over-shaking. In general, the Rumbling step (i.e. agitation) is just intended to soak all the grounds in water. Over-agitating definitely won't make better coffee, but it definitely will make more silt/sediment!

Can I use Rumble Jar to make iced coffee?

Of course! Cold brew makes for an excellent iced coffee, and it's super easy to make with a Rumble Jar. Just brew a batch normally in your Rumble Jar, but make sure to use more grounds in the filter than you normally would. Consider filling up the filter to the Concentrate Notch. The reason is that once you pour your brew over ice, the ice starts to melt and dilute your coffee, so starting with a a stronger concentrate will counteract any watery taste.

How much coffee fits in the filter?

By weight

Filled to the Normal Notch: roughly 1.5 ounces of ground coffee
Filled to the Concentrate Notch: roughly 3 ounces

By volume

Filled to the Normal Notch: roughly a half cup (~120 mL)*
Filled to the Concentrate Notch: roughly a full cup (~240 mL)*

For more on the insanity of using "cup" as a measurement tool, have a look at this HuffPo article or this Wiki article about all the varying definitions of a cup.

I noticed some dry grounds in my filter after brewing. How can I fix that?

We've seen this happen a few times with certain well-known and affordable brands of finely-ground coffee. After brewing, you might notice some of the grounds in the center of the filter still appear dry. Well, that's because they are! If you use those kinds of beans and notice this happening, here are a few fixes for your next batch (try them individually, in this order):

1) Fill up water level so it covers the cap. Coffee grounds float, so this ensures the grounds will be under water while they're floating in the filter. 

2) Give 2-4 more shakes (the standard end-over-end vertical shakes).

3) If the 2-4 more vertical shakes didn't work work, try giving it two horizontal shakes on your next batch. This loosens up the grounds that might be sticking to and blocking the holes of the filter.

4) Consider using coarse grounds. They're recommended for cold brew anyway, and we've never seen dry grounds occur when brewing with coarse ones.

General cold brew questions

Why is cold brew coffee so hot right now?

A lot of folks find it just plain-old tastes better. The secret is that cold water extracts ~70% less acid from the coffee grounds than hot water, which means that your coffee ends up tasting a lot less bitter. #science  So if you're new to cold brew, get ready to enjoy a smoother, sweeter flavor of coffee.

How long should I steep my cold brew?

If you're steeping in a refrigerator: 16-24 hours.
If you're steeping at room temperature: 8-12 hours.

How should I grind my coffee beans?

While not totally necessary, coarser-ground coffee is preferred instead of finer-ground coffee for two reasons: 1) coarse grounds result in fewer particles (aka "silt" or "sediment") winding up in the drinkable brew, and 2) finer grounds have a tendency to "over-extract" (a fancy term describing a brew that's overly bitter and pungent). If you're familiar with the ground size typically used in a French Press, Chemex, dripper or percolator, you can basically just use that same size. 

You can still make cold brew just fine if you're using fine grounds in your Rumble Jar though. Other than a little extra silt in the bottom of the jar, you might not even notice the flavor difference. If it tastes over-extracted, you can also shorten the steeping period to make the brew a little bit sweeter.

And specifically for the fine ground folks who are sensitive to silt in their coffee, our Rumble Jars do come nestled in a 100% cotton bag that doubles as an optional second-stage filter. The second-stage filter does a phenomenal job at filtering out the excess particles, but it's an added step that could be a bit overkill for the average person.

Do I need a special type of coffee to make cold brew?

Nope! It's entirely up to you which type of coffee you use in cold brew. The one caveat is that it's better to use coarse grounds instead of finer grounds. We do recommend experimenting with a few different roasts or flavors though, because cold brew tastes quite a bit different than your typical hot coffee. We've heard reports of folks discovering a preference for darker roasts for their cold brew, since that adds a bit more strength to counteract cold brew's sweeter flavor and lack of acidity.

But what if I like my coffee hot? 

We'll let you in on another top-secret umm...secret. You can indeed make cold brew and then heat it up. It won't suddenly turn bitter and lose its sweeter flavor. That's because the acidic compounds reside in the coffee grounds, so once they're removed (and please don't forget to remove those grounds before heating!), you can prepare your coffee any way you like. So go heat it up and add whatever else you normally would to your hot coffee. Our bet is you'll find yourself needing less sweetener than you did before.  

Does cold brew generally have silt?

Only the good stuff! Unfortunately if you removed all silt (aka "sediment") from cold brew coffee, you wouldn't have all that much coffee left over...and what you did have left over wouldn't taste all that good! The silt is caused by tiny coffee particles sneaking through the holes in the filter. These particles are also found in traditional hot-brewed coffee, but you just don't notice them as much because the heat disperses the particles throughout the cup. They're still there, but you just end up drinking them. Cold brew's long-steeping process results in this silt sinking to the bottom. We've been warned by our cold brew expert advisors Jittery John's that silt is a natural feature of cold brew coffee, and if you eliminated all of it, you wouldn't like the result! 

Should my cold brew taste watery?

If you're used to drinking hot coffee (and particularly if you prefer strong, dark roasts), there's no question cold brew will taste different. It should taste lighter, sweeter and more balanced, but it should not taste watery. If you're finding it tastes watery, the best solutions are to increase your steeping time to a full 24 hours, ensure all grounds in the filter are initially wet, and potentially use a darker type of bean. Regardless, it will be impossible to replicate the more bitter and acidic taste of traditional coffee, so if that's what you're craving, hot coffee might be right for you.

How long can cold brew be stored?

Cold brew can be stored up to two weeks in your fridge (as long as the grounds have been removed). That's part of the reason we designed our filter to work in tandem with the world's best storage container: the Mason jar. Those time-tested, leakproof, airtight seals will keep your coffee fresh for a while. So don't worry about brewing too much coffee or even a batch of concentrate to use throughout the week. Just make sure the grounds don't steep for longer than 24 hours, or else it could taste a little funky. 

Isn't iced coffee the same thing as cold brew? 

Nope. Iced coffee generally refers to a standard drip hot brew which is then poured over ice to cool it down. Since the coffee is originally brewed with hot water instead of cold, it's more acidic and tends to have a more bitter taste.

If it's so easy to make, why do stores charge a buck or two more for it than hot coffee? 

We have no idea.  

Product questions

Why do you use standard Mason jars?

We intentionally designed our Rumble Jar filters to work with Mason jars because 1) they're the best drinking/brewing/storage vessels ever made, and 2) they're easy and affordable to replace in case you lose or break it. Cheap and awesome is a combo we love! 

What size are the Mason jars?

Rumble Jars include a totally-standard, quart size (32oz) wide-mouth Mason jar. in case you need a replacement Mason jar, the key things to look for are WIDE MOUTH (i.e. not regular mouth) and STANDARD (i.e. not the more obscure shapes/sizes). These jars are among the most widely available verisons you can find and they're very affordable. But feel free to send us an email in case you have a question about a particular Mason jar model. 

Is Rumble Jar dishwasher-safe?

Yes. You can clean all components in a dishwasher or by hand.

What's up with the bag that comes with the Rumble Jar?

When you receive your Rumble Jar, you'll find it nestled comfortably inside of a 100% cotton filter-bag. DO NOT THROW THAT BAG AWAY! That bag functions as a pretty fantastic (and totally-optional) "second-stage" filter.

How do I use the filter-bag? Once you've brewed a batch of cold brew in your Rumble Jar and removed the filter+cap component, you can add an optional step where you use the filter-bag to strain your batch of cold brew a second time to remove additional silt/sediment and produce a clearer-looking brew. Have a look at our FAQ about silt for more on that topic.

Isn't this extra step time-consuming and anti-Rumble Jar simplicity? Perhaps...and that's why it's completely optional. But we also spoke to a few folks who preferred a clearer-looking cup of coffee with as little sediment as possible, so this extra filter is really there for those folks. You may find it helpful if you only have finely-ground coffee available, since that tends to produce more silt/sediment than the coarse grounds recommended for cold brew. 

Personally, neither of us use the second-stage filter all that often because we mostly brew with coarse grounds, and we're also fairly used to the sediment that's characteristic of cold brew. But if you use finer grounds and want a surefire way to get rid of extra sediment, give that secondary filter a go! And if you have no need for a second-stage filter, you can always repurpose it as a bag for like, storing stuff.

Why are there two small lines on the metal filter?

The lower line is called the "Normal Notch" (our creativity was running on overdrive when we named it). That line is a rough approximation for how high you should fill the grounds in the filter if you're making a standard brew that you won't dilute later with water. It's not an exact science though. It's more of a visual guide to help you eyeball your future batches so you don't need to waste time using a scale or measuring cups.

The higher line we (again, quite creatively) call the "Concentrate Notch". Filling the filter with grounds to this height is a good guide for brewing a batch of 1-to-1 cold brew concentrate. "1-to-1" means you add one part water to one part concentrate to dilute it down to drinkable coffee. Folks use this method to minimize the amount of brewing they need to do. Some people like to drink their cold brew at this strength without diluting it, but new cold brew drinkers should beware that concentrate packs a serious punch even though it might not taste like it!

Again, treat the notches as guides and not as a recipe dictating exactly the amount of grounds to use. We designed Rumble Jar to help you experiment and figure it out for yourself, so feel free to vary your inputs and brewing methods.

Why aren't there any holes in the bottom of the filter?

Most filters have holes in the bottom that match the holes in their walls. Instead, we designed the bottom of the Rumble Jar filter to feature a hole-free dish that we call a "silt pan". When you're removing the filter from the jar, that silt pan collects some of the excess sediment and prevents it from draining into your drinkable brew. If there were holes in the bottom, that sediment would immediately drain out into your coffee. Our silt pan certainly doesn't capture all of the silt/sediment, but we were definitely able to notice a difference.

How much coffee does a batch of cold brew use?

"It depends" is a lame answer, but it definitely does apply here. Being prescriptive about the correct coffee-to-water ratio is impossible (and anyone telling you they know the answer is just making it up!). It's highly dependent on your ingredients (beans, how they're ground, roasting method, etc.), the brew method (time, fridge vs room temp, type of water, etc.) and most importantly your individual taste preference. So if you Google it, you'll see an incredibly wide array of opinions about the correct ratio. 

So our best advice is to use your Rumble Jar to figure it out yourself. We've included those two notches (i.e. those short horizontal lines) in the metal filter as guides, not as prescriptive tools. They're there to help you eyeball your grounds as you prepare a batch and roughly figure out how much you personally prefer. We've found that the vast majority of cold brew drinkers prefer to fill up the filter with grounds somewhere in between those two notches.

The lower notch ("Normal strength") is our best guess for where you'll want to start (~1.5 ounces of coffee grounds). Fill your grouds to that line, drink a batch of cold brew and then reassess to figure out whether you want more or less grounds on your next batch.

The higher notch ("Concentrate strength") holds ~3 ounces of grounds, and it's a good starting place for making concentrate. Some folks like to drink concentrate without diluting it, just beware that cold brew is a whole lot more powerful than it tastes! 

Shipping questions

What shipping carriers do you use?

Unless noted otherwise, we use USPS for all shipments, domestic and international.

How long will shipping take?

Domestic: For the vast majority of the US, shipping will take 2 business days from when we hand it off to USPS until it's delivered to you. More remote US locations might see this timing stretched to 3 business days.  To figure out your specific timing, have a look at this neato map.

International: We send packages via USPS' Priority International service, and they quote 6-10 business days for delivery. Keep in mind that customs delays can happen and also that the package will be handed off to your local mail carrier for final delivery, so those issues can occasionally extend the timing beyond 10 days. In our experience though, Priority International has done a great job of delivering the vast majority of customers' packages quicker than 10 business days.

Do you ship internationally?

Because so many folks from abroad were awesome about asking us for Rumble Jar, we now offer international shipping to a whole host of countries. If shipping isn't available to your country, please send us a message and we will look into the policies and costs and let you know if we can add it. 

IMPORTANT: Our international shipping costs do not include customs fees or taxes. Sorry about that! So, just make sure you take into account any additional fees and taxes charged by customs in your country, as well as for ensuring the imported product complies with your local laws. Thanks for your understanding!

Random questions

Why do you keep spelling Mason jar with a capital "M"?

Although masonry professionals are also allowed to use them, Mason jars actually get their name from their 19th century inventor, a fellow named John Landis Mason. More about him and the fascinating history of Mason jars can be found on this Wikipedia page. You might need a full Rumble Jar in order to read the article in its entirety.

What's a "cup"?

We recently discovered that we have no idea. We thought we knew what a cup was, but after getting into the coffee business and trying to make use of a cup as a measurement tool, we're now much more clueless than when we first started. If you're interested in knowing why, please take look at this HuffPo article or this Wiki article.