Biomass format guide
RUF Briquettes: The Rectangular Wood Briquette Format
A closer look at the most widespread briquette format on the market: its brick shape, why it stacks and transports so efficiently, and how it compares to other formats such as Pini Kay.
⚠️ Note: this isn't currently part of our regular product line. This page is informational — if you're sourcing briquettes, get in touch and we'll let you know whether we can help.
RUF briquettes are one of the most widespread formats of compressed wood biomass used for domestic and industrial heating. The name comes from RUF Briquetting Systems, a German manufacturer of hydraulic presses whose rectangular design became, over time, a generic industry term for any briquette with that brick-like shape, regardless of the actual press or supplier behind it. This page explains what defines the RUF format, why its geometry is so practical for stacking and transport, and how it compares to other common formats such as the hexagonal Pini Kay briquette.
At a glance
| Shape | Rectangular, brick-shaped, flat faces and straight edges |
|---|---|
| Name origin | German briquette press manufacturer RUF; now a generic industry term |
| Typical use | Wood stoves, domestic boilers and some industrial applications |
| Stacking advantage | Interlocks with minimal gaps, like construction bricks |
| Comparable format | Pini Kay briquette (hexagonal cross-section with a central hole) |
| Genuine alternative at Maderas Caamaño | Wood pellets aligned with the ENplus standard |
What is a RUF briquette?
A RUF briquette is a compact block of pressed wood with a rectangular, brick-like shape, typically with straight edges and flat faces. It is made by compressing sawdust and wood shavings under high-pressure hydraulic presses, without added binders or adhesives: the pressure and heat generated during pressing cause the wood's own natural lignin to act as a binder. The result is a solid, dry, dense fuel intended to replace traditional firewood, offering more even combustion and taking up less storage space than the same amount of energy in logs.
Why the rectangular shape makes stacking, transport and storage more efficient
The main advantage of the RUF format over other briquette geometries is purely physical: because each piece is a rectangular prism, they interlock with almost no gaps, much like bricks in a wall. That allows them to be stacked in stable, even layers on a pallet, makes better use of the interior volume of a box or bulk bag, and reduces the amount of wasted air space during road transport compared with round or irregularly shaped formats. The less air travels inside a vehicle or container, the more fuel fits into the same journey, which generally favours this format's logistical efficiency over others. That same rectangular geometry is also practical for the end user, not just for the pallet: because they don't roll and have no irregular edges, RUF briquettes can be stacked next to a stove or boiler much like cut firewood, in neat, self-supporting rows, without special racks or extra volume allowances for air gaps. That predictability of shape and size also makes it easier to estimate at a glance how much fuel remains on hand, something that is harder to judge with irregularly shaped firewood, where a stack's apparent volume and its actual usable fuel content can diverge quite a bit.
Typical uses
RUF briquettes are used mainly in domestic wood stoves and residential biomass boilers, where their size and shape allow comfortable manual loading, similar to a cut log. They are also used in some industrial boilers and heating processes that call for a solid fuel of consistent density and low moisture content, where the uniformity of the format helps deliver more predictable combustion than natural firewood, whose shape, density and moisture vary more from piece to piece. Because each briquette burns in a broadly similar way to the next, users generally find it easier to judge how often to reload a stove or boiler than with mixed, irregularly sized logs.
RUF vs Pini Kay: two formats, one shared principle
The other major briquette format commonly found on the market is the Pini Kay briquette, with a hexagonal cross-section and a central hole running through the piece from end to end. While the RUF format prioritises brick-like interlocking to optimise palletising, the Pini Kay format — also press-formed without additives — makes it easier to split the piece into smaller chunks thanks to that central hole, and its hexagonal cross-section offers a different kind of stacking stability, though typically with more air gaps between pieces than the rectangular format. Neither format is objectively better: the choice usually comes down to the specific stove or boiler, the user's handling habits, and the transport logistics available. You can read more in our pages on Pini Kay briquettes and the general overview of wood briquettes.
Biomass alternatives at Maderas Caamaño
RUF briquettes are not currently part of the Maderas Caamaño product range. We do, however, produce other biomass fuels from Galician wood that can serve similar heating needs. Our wood pellets, aligned with the ENplus standard, in 6mm and 8mm diameters with under 10% moisture content, are designed for stoves and automatic-feed boilers. For those who prefer a fuel closer to traditional firewood, we also produce oak and eucalyptus firewood, as well as compressed hardwood logs, available in a range of packaging formats.
Frequently asked questions
What does RUF mean in wood briquettes?
RUF comes from RUF Briquetting Systems, a German manufacturer of hydraulic briquette presses. Its rectangular, brick-shaped briquette design became so widespread in the industry that "RUF briquette" is now used as a generic term for that shape, regardless of which press or supplier actually made it.
Do RUF briquettes work in any wood stove?
Most stoves and boilers designed to burn firewood or wood briquettes can use RUF briquettes, since their size is similar to a cut log. It's always worth checking the appliance manual and following its loading and ventilation guidance.
How do RUF briquettes differ from Pini Kay briquettes?
Mainly in geometry: RUF is rectangular and solid, designed to interlock with minimal gaps like a brick; Pini Kay is hexagonal with a central hole that makes it easier to split into smaller pieces. Both are formed by pressure alone, without added binders.
What biomass alternatives does Maderas Caamaño offer?
While we don't supply RUF briquettes, we do produce wood pellets aligned with the ENplus standard, along with oak, eucalyptus and compressed hardwood firewood, available in a range of packaging formats.
