Tips for improving paintbrushes

By Tom Pawlak



Tip 1—Paintbrushes are often used to apply epoxy to small or irregularly shaped surfaces, or to wet out fiberglass cloth. Unfortunately, typical paintbrushes are too soft and flexible for this task, especially in cool weather when the viscosity of the epoxy is higher.

Stiffer bristles move the epoxy along better. We often modify new paintbrushes for epoxy application by cutting away 1/3 to 1/2 of the bristle length (below). Shortening the bristles creates a brush “with an attitude” that moves the epoxy along and spreads it uniformly, reducing drips and runs. 

Tip 2— We go through many 1" wide china bristle brushes because they are readily available, inexpensive, and we don’t have to clean them when we’re done. However, they shed bristles badly. To overcome the frustration of “hair loss” we use a trick that glues the base of the bristles together.

To make this process more efficient, we modify a dozen or more brushes at a time by sticking the handles into a cardboard box (above). We mix a small batch of epoxy, add acetone or lacquer thinner at about 10%–20% by volume and apply the diluted epoxy to the base of the bristles with an 807 syringe. This saturates the bristles and glues them together. The syringe can be inserted between the bristles, allowing the epoxy to be injected into the center of the banded bristles. The thinned epoxy wicks between the bristles better, and since this isn’t a load-bearing project, we don’t need to worry about compromising the strength of the epoxy by diluting it. After the epoxy has cured, we use the brushes confidently in applications where we can’t afford to have stray bristles show up in our coatings.

Epoxyworks 16 / Fall 2000

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