Wood Slabs are pre-machined placeable crafting materials the size of half a block with a wooden texture.
They can be produced from nearly any type of uncorrupted Wood or Logs in a Processor. These flammable Slabs can be used for crafting, for building purposes, to be processed into Wood Rods and as a Fuel (the latter is not actually recommended).
How to obtain Wood Slabs
1 Wood Slab can be processed further into 4 Wood Rods if needed.
You do not need to unlock any crafting recipes in order to process materials in the Processor. Simply carry uncorrupted Wood blocks and/or Logs in your inventory/bag or in any quickslot and then activate a Processor that has been placed into the world by looking at it and clicking your right mouse button or typing "f" as the default key.
Check what items you can process that you're currently carrying in your inventory by checking your inventory window after activating/using the Processor in the game-world. This window will display a sorted list of everything you are carrying and also of what you have equipped.
The topmost section of the list will be labelled "Processable", and by hovering with your mouse button over the icons listed, you will be shown what these items, blocks, materials etc. can be processed into in the Processor.
This list will not include materials nor items that are stored in a storage container or placed nearby. You will have to take them out at first and move them into your inventory or quickbar if you want to process them.
Each Processor can be filled with 21 stacks of items (or materials) in its queue to be processed. If you hold down the "Sprint" key (Left Shift by default), you can process 5 times as many materials at once, just like in the Crafting Menu.
It will take some time for each material to be processed - both the time that one item(-stack) and all of them in the queue will take to be done is shown in the Processor window beforehand.
How to use Wood Slabs
You can place Wood Slabs into the game world just like they are, like any other type of crafted block, by putting (a stack of) them into a slot of your quickbar, selecting this quickslot by number or scrolling and by then clicking your right mouse button while pointing at the spot where you want to place them.
Wood Slabs can be rotated in all directions by holding "R" (as the default key) and moving the left mouse button. The chosen rotation angle can then be "locked" too by simply typing "r", so that all items of the same stack will be placed facing the same direction.
You won't need to equip any Power Cells to pick up Wood Slabs that have been placed. Of course you won't be able to pick up such half-sized blocks on game worlds, on player claims or in Adventures where your Permission rank is not sufficient (mainly when you are merely a visitor), which can only be changed by the owner of the game world, the respective claim owner or Adventure creator.
Wood Slabs can be used to create holes that are too small to let any Creatures slip through. However, Loot Bags can usually fall through such holes the size of only half a block. Because of this, slabs that are placed upright are often used as a bottom of kill-traps. Please note that this does not always work without fail. Once in a while even large Creatures can fall downwards through such holes, while Loot Bags might occasionally get caught on the edges of slabs and will not drop down.
Wood Slabs are used for many crafting recipes in your Crafting Menu (to be opened by pressing "q" as the default key), for example to craft Stone Mining Cells, Basic Extractor, Forges, Stone Chests, Wood Book Shelves, Wood Planters, Wood Stairs, Wood Roofs, Wood Fences, Wood Trap Doors, Wood Tables, Wood Chairs, Wood Stools, Wood Gates, Rustic Wood Doors, Wood Signs, Wood Plaques, Wood Floors, Tile Wood Floors, Decorative Wood Floors, Decorative Wood Walls, Wood Gravel Walls, Blue Wood Walls, Red Wood Walls, Yellow Wood Walls, all types of Fireworks except for Haunted Fireworks, Haunted Floors, Haunted Roofs, Haunted Stairs, Blue Adobe Roofs, Red Adobe Roofs, Yellow Adobe Roofs, Stone Signs, Iron Fences, Iron Gates, Bungalow Doors, Bungalow Windows, Medieval Chairs, Medieval Doors, Medieval Tables, etc.
Wood Slabs can also be used as a Fuel for any Forge, but this is not recommended. You might rather want to use Wood Rods as a Fuel instead, since this is much "cheaper". Wood Slabs are tier 1 Fuel and burn as slowly as any common block of Wood or Leaves.
4 Wood Slabs are necessary for each melting/hardening process in the Forge, and they can smelt 1 Lumite Ore into Lumite bars within 1 minute, 1 Diamond Ore into 1 Diamond bar in 1 minute too, 1 Iron Ore into 1 Iron Bar within 20 seconds, 1 Obsidian Ore into Obsidian bar in 20 seconds as well, and 1 Bone into 1 block of Fossils in 30 seconds, just to list a few examples.
Slabs, like all placeable objects and blocks, can also be put on display by placing them into the slots of display containers like Placemats, Stone Wall Shelves, Hidden Temple Altars, Galactic Grav-Chambers, Frozen Containers, Holiday Decorative Trees, Snow Buried Containers, Wood Planters, Flower Pots or the like, where they will usually be reduced in size while on display.
Wood Slabs are flammable
Attention: blocks of Wood Slabs are flammable! When placing Wood Slabs close to (or especially directly above) torches or any other items with open flames or fiery blocks like Hardened Lava, Wood Slabs can easily start to burn in hot environments that make a heat meter show up, like Oceans, Jungles or the Lava layer, but also in much cooler Swamplands.
Placing several torches or heat sources with open flames next to each other can even raise the chances to set flammable blocks on fire. Liquid Lava or Fire Bombs will immediately set Wood Slabs on fire.
If Wood Slabs start burning, the flames are then able to spread to other nearby flammable blocks, even across gaps of 1-2 blocks on worlds and player claims where the "fire spreading" option is enabled. This way a whole wooden building or forest (especially Wildwood, Parchwood and Shorewood) can burn down in the worst case.
Fire cannot be extinguished by using liquids, but it can be stopped from spreading by claiming the area and making sure that the claim (advanced) option "fire sim/spreading enabled" is disabled (by default). Fire Bombs will have no effect on these claims either.
It is also possible for owners of the game world (F2P players included) to toggle the spreading of fire on a whole game world in the basic world options ("edit world" and "disable fire spread"). Another option to stop fire from spreading would be to create forest aisles/swaths wide enough so that the flames cannot leap over.