The newly drywall'ed attic is coming along quickly and soon will just need to have its seams finished. Having used the spines from pallets as the nailing plates on the attic ceiling, we're left with a lot of thin hardwood pallet boards with which we can cover the seams - but these go up like tinder and would undo everything we've accomplished in drywalling. A bit of research into alternative fire proofing methods reveals silica beads as a possible solution.
First they need to be crushed, but the pellets aren't as cooperative as we hope. Using a hammer or any very primitive crushing method results in pellets scattered across the room, largely intact. We instead acquire a used pepper grinder; It works perfectly.
The compound - sodium silicate, also known as water glass - can be crafted using these silica beads ground into a powder and dissolved in heated water and sodium hydroxide (which can often be found labeled as typical household drain cleaner). The product when applied to wood should petrify it - encrusting its organic faces into stony ones.
Two batches of the chemical are mixed up to test different ratios for the compound - the second using much less water than the first.
From left to right: untreated poplar (control), sodium-silicate poplar, high concentration sodium-silicate poplar
The above samples were left in the fire for about 3 minutes. Eventually even the most fire"proof" of things will catch fire. The untreated took roughly 90 seconds to catch flames while the other two produced a thick char but did not retain flame. The higher concentration of additives seems to have been slightly sturdier - and now that we know this is a plausible operation, the proportions can be tested more thoroughly.