Chalk in Cairn is a consumable resource that boosts your grip on flat surfaces during climbs. Since you won't find chalk lying around on Mount Kami, you'll need to manufacture it yourself using your companion Climbot. The process is straightforward once you understand the mechanics, though it does require some planning ahead.
Quick answer: Open your backpack while on the ground, select an item to compost by holding Y or Triangle, wait 12 hours for Climbot to process it, then collect the chalk packet from your backpack menu.
What chalk does
When you apply chalk by holding right on the D-Pad, it grants you "Extra Grip" for a limited number of hand placements. The display shows a counter (for example, "Extra Grip: 12") that decreases by one each time you place a hand on a surface. Your feet don't consume chalk, only hand placements do. This extra grip lets you cling to fairly flat rock faces that would normally be impossible to hold, making chalk essential for sections without natural crevices or handholds.
You can apply chalk at any moment during a climb, even mid-grip, and the buff persists across rest periods. If you rest at a piton and then continue climbing, any remaining chalk on your hands stays active.
How to make chalk with your Climbot
Step 1: Move to flat ground or hang from a piton. You cannot access your backpack while actively climbing.
Step 2: Open your backpack by holding down on the D-Pad. Use the left stick to browse your inventory items.
Step 3: Highlight any item and hold Y (or Triangle on PlayStation) to compost it. Your Climbot will begin processing the material immediately, starting a 12-hour timer.
Step 4: Wait for the timer to expire. You can speed this up by composting additional items, which reduces the remaining time by 15 minutes per item (though you still only get one chalk packet at the end).
Step 5: Once the timer finishes, return to your backpack menu and hover over your Climbot. Press A or Cross to collect the chalk packet. You must have an empty slot in your chalk bag for this to work.
Step 6: Open your inventory and select the chalk packet. A portion of chalk transfers from the packet into your chalk bag, which you can then use during climbs.
You can carry multiple chalk packets in your rucksack and refill your bag whenever you rest at a piton. This lets you stockpile chalk before tackling difficult sections.
What to compost
Plastic wrappers are the ideal choice. You get them by eating food items like chocolate bars, and they serve no other purpose. Many wrappers even note in their description that they should be composted. You'll also find loose wrappers scattered around the mountain.
Tin cans and other waste items work just as well. Since these are pure garbage, composting them feels natural and doesn't waste anything useful.
Plants and mushrooms can be composted if you're in a hurry, but they're often more valuable for eating or other uses. Reserve these for emergencies.
Avoid composting items that have survival value, like food or tools. Stick to waste whenever possible.
Speeding up chalk production
The base composting time is 12 hours. If you need chalk faster, compost additional items to shave 15 minutes off the timer for each one. You won't produce extra chalk this way, but you'll finish sooner.
To pass time efficiently, rest on the ground by holding LT (or L2) and down on the D-Pad, or sleep at your Bivouac tent. Both methods let time advance while you wait for your chalk to finish processing.
Planning ahead is key to never running out of chalk. Start composting waste items early in your climb, and by the time you reach difficult sections that demand extra grip, you'll have multiple chalk packets ready in your rucksack.
