Your Questions, Answered

FlameWise makes two models:

Campfire Size — 3 feet wide × 2 feet tall. Capacity is just under half a cubic yard. Great for individuals, small properties, and first-time kiln owners.

Burn Pile Size — 4 feet wide × 30 inches tall. Capacity is just under one cubic yard. Ideal for larger properties, conservation districts, farms, and community burns.
At a full fill, the Campfire size produces around half a cubic yard and Th Burn Pile size about one cubic yard - however, most people don't fill the kiln completely.
In a typical session the Campfire size produces around a quarter to a third of a cubic yard, and the Burn Pile size produces around a half to two-thirds of a cubic yard.
Flame cap kilns process feedstock at roughly 5 to 10 times the volume of the kiln. So for a Burn Pile size kiln producing close to one cubic yard of biochar, budget somewhere between 5 and 10 cubic yards of feedstock, depending on how dense or "fluffy" the material is.
Yes — customers have done exactly that. Two kilns can be connected side by side to accommodate a larger burn pile. We've seen this used with tractor-loaded material as well. Hand-loading tends to produce less smoke (because you add material gradually and maintain the flame cap), but machines can be used to move bulk material right up to the kiln edge.

Safety note
Use clean, unpainted, untreated wood — branches, prunings, slash, orchard waste, Douglas fir, and similar dry woody material all work well. Eucalyptus and other agricultural woody waste are fine too.

Do not use painted, stained, or pressure-treated wood, as burning those releases toxic compounds.
These materials create insulating air pockets and do not process well in flame cap kilns. Sawdust is better handled with a briquette maker or added to compost. Leaves and dry needles have the same limitation — save the kiln for solid woody material.

We have not found an upper limit. The founder has done dozens of burns in her own kiln without issue. Comparable flame cap kiln designs (like Kelpie Wilson's Ring of Fire) have been used for 100+ burns and keep working. These are not single-use or limited-run tools — treat them well and they should last for years.
Yes, mild surface rust will develop over time — but this does not affect performance. The kiln can be left outside under a tarp through winter without issue. It's a great option for community or communal-use programs that need a simple storage plan.

Budget about 100 gallons per cubic yard of biochar produced when you're starting out. With practice and technique, many people get this down to 50 gallons per cubic yard or less — for example, by covering the kiln with a silicone-coated fiberglass welder's blanket at the end of the burn to trap steam and reduce the water needed.

For a typical Burn Pile size burn (½ to ⅔ cubic yard of char), plan on 50–70 gallons as a practical starting estimate.
Personal protective equipment: leather work gloves, leather boots, long sleeves and pants in cotton or wool (no synthetics — they can melt), hat with brim, eye protection, hair tied back. Wear a breathing mask during quenching to avoid inhaling micronized carbon.

Useful tools:
• Thermal camera (large screen) — to find hot spots in char
• Infrared temperature gun — to check kiln temperature
• McLeod hoe — for raking out
• Silicone-coated fiberglass welder's blanket — to cover the kiln and reduce water needed at quench

Always have adequate water supply before igniting. Supervise the site for 30–60 minutes after the burn is complete.

Both kiln sizes consist of 12 panels (6 interior, 6 exterior) are flat and stack compactly — they fit in the back of a standard car. This makes the kiln easy to transport and store in a shed, garage, or under a tarp outdoors.
The Burn Pile size kiln has a combined weight of about 95 lbs. and the Campfire size is about 50 lbs.

To place an order, use the contact form. Let us know the size you want and your full shipping address, and we'll send an invoice you can pay online through Clover, our payment system.

We fabricate each kiln to order (we don't keep stock on hand). Fabrication takes approximately 3 weeks, and shipping adds about 1 week, so plan for roughly one month of total lead time from payment to delivery.
Yes. If you're in or passing through the Seattle area, pickup is available and sidesteps shipping costs entirely. We also occasionally coordinate handoff meetups along routes we're already traveling — just ask and we'll see what we can work out.
Yes — FlameWise ships to customers across the US. We've shipped to Colorado, Idaho, North Dakota, Texas, California, Minnesota, and beyond. Contact us with your zip code and we can give you a shipping estimate.
Yes. We work with conservation districts, universities, nonprofits, and grant-funded programs regularly. We can provide itemized pricing documentation for grant applications. Some grant programs require that orders not be placed until the grant is contracted — we can hold a quote and initiate fabrication once payment is received. Reach out and we'll work with your process.

Burn time varies based on feedstock type, moisture, and kiln size - budget at least 3 hours and up to 6. The smaller Campfire kiln will generally complete a burn faster than the Burn Pile size under the same conditions. You must remain on-site and attentive during the entire burn, and should plan to supervise for 30–60 minutes after quenching to ensure full extinguishment before leaving.