Polyurethane
Polyurethane is made from organic and synergic resins that are mixed with a solvent. They are transparent but have a yellow hue. Polyurethane is water, fungus, and mildew resistant. It also will resist abrasions, heat, and chemicals.
It comes in flat or gloss sheens and is sold in most hardware stores. There are three different types of polyurethane:
Wipe-on poly – great for curved surfaces and detailed trim. Especially beneficial where a brush might lay on too thick of a coat and spraying is out of the option. Not a great choice for areas that might endure wear.
Brushing poly – great for flat surfaces and areas in where the coats need to built up. This is ideal for areas where there might be high wear.
Spray-on poly – great for hard to reach areas that don’t receive high use, as it’s finish is not as durable as the brushing poly. Extra caution has to be taken to avoid drips and overspray.
The advantages of polyurethane are:
- Durable, clear finish
- Excellent chemical resistance
- Good abrasion resistance
- Water, fungus, and mildew resistant
- Good heat resistance
The disadvantages of polyurethane are:
- More difficult to apply than lacquers or shellacs
- Longer curing time between coats
- Each coat has to be sanded before next coat is applied
- Harmful fumes given off