To achieve a superior polymerized flaxseed coating regeneration of your cast iron cooking surface it is most important to remove built up food particles that have accumulated during the cooking process.
A scouring agent is required.
We have had a bit of a serendipitous break through at our pan research facilities in Richmond regarding best scouring techniques for preparation of cast iron before applying a seasoning oil.
In turns out that 240 grit sandpaper really hits the mark.
This fine sand paper is fast and effective and available at all hardware stores in the painters section. It can be purchased in small rolls (10cm*100cm) and costs two or three dollars.
After sanding wash the pan in warm water and dry.
Use flaxseed oil as your seasoning oil.
The application of flaxseed oil is entirely different to conventional seasoning oils and application techniques.
Warm the pan that is to be seasoned so as to "condition the cast iron" for receiving the applied oil.
Best application cloth found to date is an old cotton tee shirt cut into pads.
Cover all pan surfaces with a fine coating of flaxseed oil. Use the drier part of your application cloth to wipe back any excess surface oil.
You only require the thinnest coat of flaxseed oil.
Place the pan UPSIDEDOWN on a high oven rack.
Turn the oven up to high heat and bake the pan for 30-40 minutes at least 220-250C.
Turn off the heat and allow the pan to return to room temperature.
It is essential that the pan completes the "smoking" phase during which will see the pan smoke until the oil arrives at the "cured" stage.
Avoid laying down a thick coating of oil as only the flaxseed oil surface cures ( hardens) effectively leaving the oil beneath "underdone" and soft.
Repeat step 2 as it has been found that this double coating of polymerized flaxseed seasoning is a very effective regeneration of a cast iron cooking surface.