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April Fools Day means looking forward to a few things — toothpaste in Oreos, air horns behind doors, and Black Diamond’s yearly video. The company has a history of coming up with joke products with prank introduction videos.

But last year the prank became reality. Black Diamond (and their favorite actor, Mr. Honnold) released the Hot Forge Heated Chalk Bag. The concept is simple: combine a chalk bag and an electric hand warmer. Kiss numb fingers goodbye.

As a climber with a mild case of the circulation-inhibiting Raynaud’s Syndrome, this is a cause near and dear to my heart. If a chalk bag could save me from resuscitating my fingers on cool fall days, it would be a game changer.

But given the Hot Forge’s price and the wide availability of both good chalk bags and hand warmers, we weren’t sure if the Hot Forge could live up to the hype. So we tested it to find out.

Starting up a sport climb with the Black Diamond Hot Forge Heated Chalk Bag.

Compare the Hot Forge Heated Chalk Bag to Top Chalk Bags

Chalk Bag Score Pockets Shape Closure
Top Pick: Arc’teryx C80
Rear Zip Taper Drawcord
Black Diamond Hot Forge Heated Chalk Bag (This Product)
Rear Zip (battery) Taper Drawcord
Best Minimalist: Petzl Saka
None Bulb Drawcord
Best Closure: Arc’teryx Aperture
None Modified Cylinder Twist
Best Value: Sukoa Chalk Bag
Front Zip, Rear Zip Cylinder Drawcord

If you’d like to read more about how the Hot Forge bag compared to the other chalk bags we tested, check out our chalk bag reviews. Or keep reading for our full Hot Forge Heated Chalk Bag review.

What We Like


I had one big question when I got this bag: does the heating actually work?

The short answer is yes. The Hot Forge bag has a heating element at the front of the bag — the place that the undersides of your fingers land when you reach for chalk. The element extends into the bag like a tongue, so you can wrap your fingers all the way around it.

And it gets hot. The Hot Forge has three settings (green, yellow, and red) that correspond to different intensities. Even on the lowest setting, the heat glow is immediately noticeable.

The Black Diamond Hot Forge bag next to a Petzl GriGri.
The Black Diamond Hot Forge Heated Chalk Bag next to a GriGri for scale. Heat settings are controlled by a single button on the front of the bag. The button glows green, yellow, or red depending on the setting.

On crisp days, this bag took my hands from the edge of numbness to comfortably warm. In my experience, the Hot Forge is more effective than a conventional hand warmer tossed into a bag.

And on the highest setting, the bag puts out some serious heat. It couldn’t stave off numbness on the coldest mornings, but it makes a real difference. That’s enough for me.

It’s Still a Good Chalk Bag

All that heat doesn’t do much good if the Hot Forge can’t do what every good chalk bag does — hold climbing chalk.

But it does so admirably. The opening is wide, all the components work well together, and the chalk well is deep enough to hold lots of chalk. The heating element quickly becomes coated, which means you can chalk up while you warm your fingers.

The closure system is a simple drawstring. It’s not the best drawstring we’ve used, and it’s not as sophisticated as fancier closures like the Arc’teryx Aperture, but it gets the job done. A simple plastic bag can corral any chalk leakage in your climbing pack.

The outside of the Hot Forge is built into a series of baffles with synthetic insulation. I had no way to test how well the insulation traps heat, but it proved durable enough for hard use in my testing. It looks cool, too.

Easy to Use

Charging and using a heated chalk bag could be finicky, but the Hot Forge isn’t. Everything is intuitive and thoughtfully designed.

The rear zip pocket contains the batteries. They plug into a small cord that runs to the heating element. When unplugged, the batteries can be charged by plugging the provided charger into the same socket.

Plugging in the Hot Forge's battery pack.

Heat settings are controlled by a single button on the front of the bag. Hold down for on, press to change the intensity, and hold again to power down. The button glows green, yellow, or red depending on the setting.

It’s about as easy a system as I can imagine. The bag never turned on accidentally in my pack, and I could even adjust the heat mid-climb if necessary. For such a complex product, this one is impressively simple.

What We Don’t Like

Charging a Chalk Bag

As simple as the Hot Forge is, it’s much more complicated than a conventional chalk bag. I did forget to charge the Hot Forge before an outing more than once, and the battery and charger wouldn’t be hard to misplace.

The battery life of the Hot Forge isn’t perfect, either. BD lists the estimated runtimes by setting: 6-8 hours on low, 4-6 hours on medium, or 2 hours on high. I didn’t get to put those numbers on a timer, but especially on the highest setting in bitter cold weather, I found the Hot Forge could lose juice quickly.

Even a sport-climbing burn can take upwards of 20 minutes, which allows only a few runs on high. If you’re headed out for two or more days, battery conservation becomes a priority.

The lower settings still put out a decent amount of heat, so this may only be an issue in harsh conditions (or for those of us with truly poor circulation). All the same, the Hot Forge is yet another device to remember to charge before trips.

Charging the Hot Forge batteries along with a portable battery pack and a camping lantern.
Charging the Hot Forge batteries along with a portable battery pack and a camping lantern.

…Still Need More Heat

Although the Hot Forge makes a real difference on the wall, it wasn’t quite the game changer I hoped for. This is likely down to physics more than a failing of the product, but it’s worth noting.

When my fingers did numb out on cold days, the Hot Forge wasn’t always much help. There seemed to be some kind of threshold where the bag could no longer keep the cold at bay.

Where that threshold lies depends on a variety of conditions, but on the coldest days I found myself wishing for a higher setting. Add in the need to conserve battery, and the Hot Forge’s use can become limited.

This was only a problem on wintry days of ~40 degrees or under, when my hands would normally be bricks of ice. The Hot Forge still helps, but can’t work miracles. When temperatures drop, some suffering will still be involved.

The Price

Considering the limitations of size and use, the above concerns are relatively minor. Charging the batteries is a small price to pay for how well the Hot Forge functions, and it remains helpful over a wide range of temperatures.

The bigger obstacle for many climbers is price. The Hot Forge costs about as much as a pack of quickdraws and well more than just about any other bag on the market. Given the unique nature of the product, that’s understandable. But is it worth the money?

Conventional hand warmers are relatively cheap. Putting one or two inside your chalk bag on chilly days will have a similar effect to the Hot Forge, albeit weaker. If cold hands aren’t a severe problem for you, a hand warmer now and then might be sufficient.

Climbers with chronically cold hands may be more willing to consider the investment. I’ve used the Hot Forge for months, and so far I’ve seen nothing to make me doubt the bag’s durability. As long as it lasts seasons of reliable warmth, the price of the Hot Forge looks more appealing.

Best Uses

The Hot Forge is best suited to climbers with chilly fingers who are willing to invest in a long-term solution.

It works best on shoulder-season days. This bag won’t save you in the middle of winter, but on crisp fall days it can be the difference between suffering and sending.

The Hot Forge is best on short trips or when a power source is readily available. If you’re climbing more than two days in a row in the cold, battery life will likely be an issue. And don’t forget that the cold saps battery life from devices.


For many climbers, the Hot Forge may not be superb value. It’s a bag that only comes into its own in certain weather, and it comes with a premium price tag and some added inconvenience. If you can get by with conventional hand warmers, there’s no need to upgrade to the Hot Forge.

But I’ve never regretted snagging this bag after the April Fool’s Day release. Numb fingers are a major problem for me, especially on days when the friction is best. The Hot Forge is a welcome quality-of-life upgrade, and I’m glad to have it around.

How the Hot Forge Chalk Bag Performed in Our Testing

Mid-climb with the Hot Forge Heated Chalk Bag.

Poof Test

I filled the Hot Forge up with chalk, cinched it as tightly as I could, and gave it a squeeze to see how much chalk would escape.

The closure came in the middle of the pack. Some chalk did escape, but it’s a reasonably effective drawstring.

Field Testing

The Hot Forge is primarily useful outside, so I took it out for some cold days sport climbing and bouldering. I climbed with the Hot Forge in temperatures ranging from the high 30s to low 70s, experimenting with different settings and recording my findings. I assessed the Hot Forge for its heating capabilities as well as its performance as a regular chalk bag.

Product Specs

  • Pockets: Rear Zip (battery pocket)
  • Shape: Taper
  • Closure: Drawstring
  • Weight: 175g (with battery), 92g (without battery)

The Bottom Line

Will the Black Diamond Hot Forge Heated Chalk Bag solve all your winter climbing woes? No, it won’t.

But it goes a surprisingly long way. When the send temps come around this fall, you can bet that the Hot Forge will be going to the crag with me. It’s pricier than a regular chalk bag, but for climbers who regularly struggle with numbness, it may be worth it.

Shop Black Diamond Hot Forge Heated Chalk Bag


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