Why do we sand a wood floor? If this question were asked of flooring contractors, typical responses might include: to repair damage to the floor; to change the color; to change the finish sheen; or to protect the investment (preserving and restoring the beauty of a wood floor found under the carpet that was removed, for example).
Yes, there are even more reasons, however, the main reason to sand a floor, whether new or existing, is to give beauty to a renewable resource that can usually be repaired instead of replaced. A typical nail-down, ¾-inch, tongue-and-groove wood floor can be resanded several times by a good professional flooring contractor; most beginning floor contractors would have a tendency to sand too much off the floor, decreasing the overall life and leaving little or no wood for the next sanding.
Taken from that perspective, contractors sanding a wood floor have a huge responsibility to protect their customer's investment and make that floor last as long as possible.
Water-Based Polyurethane
Polyurethanes are today’s standard floor finish. Water-based varieties used to have a reputation for being eco-friendly (still true) but not as durable as regular polys. However, today’s water-based polys are nearly as tough as their oil-based cousins.
One difference is final color: Water-based polys dry clear; oil-based polys have a slight amber tint.
Oil-Based Polyurethane
Oil-based polys are the mainstay of floor finishing and widely used by professional finishers.
Although they’re tough, long-lasting, and less-expensive than water-based polys, oil-based polys have a higher VOC content and stronger odor during application.
Oil-based finishes appear amber in color.