Rainworks are pieces of street art that only appear when wet, featuring messages, images and interactive games that work great for a city infamous for its frequent precipitation. The idea, in part, is to encourage people to enjoy the rain, and reward those who go out and play in the gathering drizzle.

Peregrine Church creates these works which, while temporary, can last for months before degrading – the water-repellent sprays used are eco-friendly and will biodegrade when the designs eventually dissolve.

Neverwet and its analogs are not exactly new materials, nor is the idea of applying it to stenciled graffiti art novel, but the variety of Church’s work is compelling, as is his targeting of its results to different neighborhoods in an oft-soaked city, from the U District to Ballard and beyond. Some of the vignettes are simply playful images, or geek and gaming references, while others carry water usage-related messages.

Indeed, this seems the perfect set of urban settings – while Seattle has frequent rains it rarely has downpours, meaning the ground is often moist but the weather rarely so bad that it is difficult to go out and experience it.

The writing is on the walls, but only when they get wet – that is when the secret messages or hidden designs appear in these seemingly innocuous concrete surfaces, like a durable and built-in version of Neverwet graffiti.

The project is called Silent Poetry and its creators, Frederik Molenschot & Susanne Happle, have started with a high-contrast approach: organic forms hidden in strict geometric slabs, but any other patterns are equally compatible with the approach.

The underlying magic-caliber, moisture-sparked trick works whether the material is drizzled on by the rain, doused in running water, touched by steam or impacted by condensation on a hot and humid day, making for innumerable creative possibilities both inside and outdoors.

Picture a public sidewalk, parking lot or city center on the one hand or a private walkway or concrete-tiled bathroom on the other. But also consider the range of applications from wayfinding in urban settings to domestic decorations on front decks or walkways that appear with the morning dew, using either modular precast tiles or larger poured-in-place slabs.

From the designers: “The possible applications of solid poetry are various: either at home in the bathroom, in the garden, in saunas and dance clubs, where the humidity is high or public spaces like bus stops or pavements. All forms of solid poetry have in common that they change the whole setting; they are surprising and have a life of their own.”

NeverWet has been making headlines as the silicon-based spray that repels liquids from clothes and electronics, but this off-book use shows another fascinating application that may be even longer-lasting: urban art invisible until poured upon.

As part of a Home Depot competition, Nathan Sharratt decided to create stencils and spray hydrophobic NeverWet onto streets and sidewalks, resulting in areas of deflected moisture surrounded by soaked concrete. Like invisible ink, the water-repellent areas remain hidden until another liquid is applied (instructions at the end below).

Given criticism of NeverWet when applied to shoes (apparently it can discolor or leave residue) and phones (touchscreen and durability issues have been reported), this may prove to be a more persistent, if unintended, long-term application of the product.

And for any interested subversive artists, it could prove a unusual boon when bothered by police: how will the authorities justify arresting someone for spraying an invisible coating on a public surface? Meanwhile, best of luck to Nathan in the contest – a win here is surely deserved! As one reader  noted: there are practical and legal street applications of this too, potentially: “Instead of a sign saying slippery when wet… graffiti saying slippery.” That, and consider: sidewalk happy-hour signs for drink specials in the rain, or way-finding messages for seeking shelter in a storm. Many interesting possibilities.

Short-form instructions for those looking to (officially: don’t!) try this at home or in the neighborhood: “Step 1: You need a stencil. You can do something simple or use an image that includes a fair amount of detail. I created my own stencils from cardboard, but there’s no reason you can’t use a ready-made or store-bought stencil. Just know that NeverWet will get sprayed on that, too. Step 2: Place stencil on concrete. I recommend that you only try this on light-colored concrete for best results. Step 3: Spray the NeverWet into the cut-out areas of your stencil according to the manufacturer’s instructions found on the label. I did two base coats and two top coats.”