Ask the Experts

Masking Fluid: Time Frame

The Dory

Image: "The Dory" by Winslow Homer, 1887

Ask the Expert: "Is 1 week too long to leave masking fluid on a watercolor? Longer?"

A: On genuine watercolor paper or similar hard surfaces, leaving masking fluid in place for one week is normally no problem at all. It's recommended that masking fluid should be removed after 3-4 weeks, though this can vary depending on specific properties of the paper surface. Obviously, if masking fluid can be removed right away, that is best, but Grafix, manufacturer of a popular latex-type "Liquid Frisket" agrees, 1 week should be fine.

There are some measures that the artist can take to ensure clean removal without stains. Most brands of Masking Fluid have a yellow tint. This derives from a colorant added to make it easier to spot the dry mask on paper, so the artist can effect complete removal before over-painting or framing the picture. This tint can settle and concentrate at the bottom of the container, so make sure to shake or stir Masking Fluid before use to ensure any colorant is distributed evenly and will not stain paper.

Masking Fluid is formulated for use on watercolor paper, which typically has a hard, heavily sized surface which resists deep penetration by wet media. Non-standard or poor quality paper, as well as some printmaking papers might allow greater penetration of masking fluid, so where “student grade” and non-standard surfaces are concerned, there might be instances where some remnants of dry mask might be stubborn to remove. When using these categories of paper, it may be best to test masking fluid on a scrap first to identify any issues. Papers and boards with hard, smooth surfaces and heavy external sizings, like hot-pressed illustration board and plate-finish Bristol, normally facilitate easy removal of masking materials even weeks after application.

There is also a “permanent” type of masking fluid which is more like a wax resist. As the name suggests, Permanent Masking Fluid can’t be lifted and becomes a durable part of the painting. Permanent Masking fluid is colorless and does not include an indexing dye, but can be spotted by its subtle, shiny surface.

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