The Art of Floor Sanding (part 3)

Good day!

Floor bore here again.
Today i want to talk more about basic sanding techniques.
To do this you will need a good belt sanding machine, a rotary finishing machine  and an edger.
There are a few different makes of machines around and i will later talk about our machines,
but anything working properly and of good quality should allow you to get great results.
 So here we go.
Counterintuitively and contrary to what many other contractors do, we
NEVER SAND WITH THE GRAIN!
Let me elaborate on this point.
It would seem sensible practise to sand with the grain.
The thing to remember here is that any sanding will cause scratches and our job is to make sure that we remove the previous scratches with finer and finer abrasives.
The problem with sanding along the grain with our belt sander is that these scratches are very difficult to see even using our light system
For this reason we always sand at an angle across the grain.
This angle should be around 15 degrees from the line of the grain or more of an angle if the floors are very rough and need flattening (which is the other important reason to sand across the grain)
Now when we come to our next sand the scratches that we need to remove will be clearly visible.
When sanding herringbone parquet always sand at 45 degrees to the grain never straight across.
Remember the light will show you exactly where you are in terms of the state of the floor.