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Dr.
Sand has been busy. Below are previously answered
questions from the Dr. Sand's achieves:
Question:
Dear Dr. Sand,
The old timers that taught me to sand floors taught me to
use a three cut sequence. I run my own business now. I have
broken away from the three cut method. It seems that I am
using less sandpaper more time and much more finish to get
the same result as a three cut job.
Answer:
The old timers are not always right but in this case
they are. Depending on your cut sequence a "Two
Cut" job can leave deep scratches that open up the
grain of the wood and allow more finish to soak in. You have
to fill in the scratches with finish before you get a nice
even gloss on the floor. I recommend that you skip only one
grit when you are sanding. Following the advice of the NWFA,
when you look at the job, first determine what grit you
would like to finish with, then work backwards. Here is an
example...
You want to finish sanding with a 100 grit paper (or belt).
Your sanding sequence should be 40, 60, 100. If 40 grit is
not working out for your first cut go one grit coarser. In
this case it won't hurt you to skip to a 60 grit and follow
up with 100 grit.
Most guys will get into trouble if they try to short cut a
job and go from a 36 to 100 grit. It costs you more time
trying to get the 36 scratches out of the floor with a 100
grit than it would to do the job correctly.
Question:
Dear Dr. Sand,
When
I use waterborne finishes it takes a lot to build up the
finish. Screening in-between coats takes off too much
build. I tried using a used 120 grit on
one job and a 150 grit on another. Same results, I am
putting on 4 coats where I could get away with a seal
coat and 2 coats of solvent based poly. Any
suggestions?
Answer:
If you are like many contractors who like the predictability of
screen, try using a 150 or a 180 grit screen with a softer
pad. I suggest using a thick white pad. It will cushion
the screen and make it less aggressive. You will
remove less finish.
If
you are willing to try a different approach to in between
coat preparation, try this approach,
- Thoroughly
screen the bare wood after sanding
- Vacuum
and tack rag as usual
- Following
the manufacturers instructions, apply the seal coat
- Use
a 150 screen on a Virginia maroon pad to knock down the
grain raise.
- Vacuum
and tack rag
- Apply
the first coat of finish
- Use
a Virginia Maroon pad and three "Footballs"
- Apply
the second coat of finish
Proceeding
in this manner will give you superior between coat
adhesion without removing excess finish.
Please
let me know which approach works best for you.
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