Final answer:
A 'full cut' in polyurethane finishes involves sanding down existing polyurethane, typically to the bare wood or just above it, to provide a smooth surface for a new finish.
Step-by-step explanation:
When working with polyurethane finishes, a 'full cut' refers to the process of sanding down an existing polyurethane layer before applying a new finish. The level to which the old polyurethane is trimmed down can vary based on the condition of the existing finish and the specific requirements of the project.
Typically, a full cut can involve sanding the polyurethane down to the bare wood, or slightly above it, without completely removing all existing layers. This ensures a smooth and even surface for the new finish to adhere to, enhancing both the appearance and longevity of the wood item. Usually, for a full cut, you would remove all the old finish until it's almost reaching bare wood but not entirely removing the last thinly spread layer of old polyurethane.
Please note that proper safety gear such as masks and eyewear should be used during this process to protect against dust and other particulates generated by sanding. Additionally, the specific grade of sandpaper and sanding technique used are crucial for achieving the desired results without damaging the wood.