This datapack is based on the idea presented in Ethosloab's Let's Play episode #589:
"Cut blocks should be reversible to their basic forms by using a blast furnace" (paraphrased)
You can find a collection of the EthoMIX (Etho Minecraft Ideas eXplored) databacks here.
Allowing many different types of block variants, including stairs, walls, etc. to be stored as their base version goes a long way towards freeing up space in storage systems and addressing the ever-present Inventory Issue™️.
Some of the recipes have been modified slightly from the original idea to be more in line with the vanilla game. For instance, blast-smelting Cobblestone or Mossy Cobblestone variants yields Stone instead of Cobblestone (since the cobblestone "would be smelted"). Similarly, Deepslate variants will yield Deepslate rather than Cobbled Deepslate.
Additionally, there are some minor changes to the recipes which add a bit of extra convenience.
Blast-smelting Copper Blocks of any stage (including regular un-cut Copper Blocks) will advance the oxidization level by one stage as well as remove wax (if waxed). This allows you to effectively spend fuel to speed up copper aging, and reflects the real-world practice of applying heat to patina copper.
Smooth stair variants of certain blocks (Sandstone, Red Sandstone and Quartz) can be blast-smelted into the main variant of the block rather than the smooth variant. This allows you to revert smooth variants which would ordinarily be irreversible, and further reduces the final number of "basic" blocks.
All together, this datapack adds nearly 200 blast furnace recipes which allow you to save space by condensing your storage.
Each of the items in the following screenshots can be blast-smelted into the forms seen in the final screenshot.
So your chests can go from looking like this...




To like this!


