Grain Raising

Grain raising is a term given to timber floorboards affected by swelling particles of timber throughout the grain on the board.

When a timber floor is sanded many fine timber fibres are left partially detached on the surface of the timber and inside

the grain usually concentrated in the more porous and softer areas of the timber.

Wetting these fibres can cause them to quickly grow. This is known as popping the grain.

These fibres have been known to absorb some floor finishes quickly swelling or puffing these timber particles up in some cases causing

the floor to appear uneven or slightly rippled.

The puffing pattern often follows the pattern of the grain of the timber as the density of the timber throughout the grain differs creating

different levels of grain raising.

Grain raise is most common with water based finishes

as most timber readily accepts and stores water very quickly.

Cooler or wet weather can prolong the drying of waterborne polyurethanes which can leave the floor wetter for longer also contribute to further grain raising.

Waterborne polyurethanes have a different look

The also have a different feel and colour to them than the well known solvent base finishes we are used to.

They also have far thinner profile meaning they hug the surface of the timber very tightly and can make a

curve or contour possibly stand out further than it did when it was raw.

This combined with slight grain raising patterns are the cause of a rippled appearance of the floor.

Solvent Based Polyurethanes have a much thicker profile than the water base urethanes and take longer to dry.

The thickness and long drying time of the solvent polyurethane allows it to self level to a certain extent.

This gives a flatter looking surface in most cases and is far superior to Water Based.