This one's a bit of a collectors item, folks. Over the years I've had a frustrating and turbulent relationship with masking fluid, to the point that I only tend to use it once in a blue moon. It really is ghastly stuff and I find leaving areas of white by painting around them creates more natural edges to the shapes. For very fine areas of white, like boat masts or wildflower stems, I find that using titanium white offers greater control and more predictable results.

However, there are times when masking fluid really is the best solution. Yesterday I started a large 'letterbox' format painting (98cm x 28cm.) The scene, overlooking Swanage bay in Dorest, includes a large area of sea, in which stands a number of supports and stanchions on the existing pier, but especially the old pier, the remnants of which are in the foreground. It is important to preserve the white of the paper for these, as they are glowing warm and bright as they reflect the evening sunshine. To paint an area of this size I like to pre-wet the area and then drop the pigment into that, building up long flowing brushstrokes to suggest the gentle movement of the sea; it is simply not possible to avoid all those little posts and trying to cut around each one using a wet-on-dry technique would not deliver a smooth sea-like wash.

So, I decided to deploy the masking fluid, most of which had dried up in the bottle. Once I had removed a large plug of congealed, foul-smelling latex, I poured a little out for ease of use and carefully applied it with a fine brush, which I kept dipping in a solution of warm water and dish washing liquid to avoid the fluid clogging up the brush hairs (still, use an inexpensive one that you don't mind losing should this happen.) Once completely dry, I was able to paint the area wet-on-wet, with the freedom of application and brushstrokes that a passage like this requires.

I'm pleased with the result, but I think the bottle of masking fluid may sit in a darkened corner on my shelf for another couple of years. What are your experiences of using it? Love it, loathe it?