A while back when I was getting started at making terrain, I glued some textured green model railroad paper to a big square of foam to serve as a generic outdoor encounter area, and it’s served its purpose well. Every time I look at it, though, I find myself wanting something with a little more detail and variety.

I’ve seen a number of videos on making roll-up battle mats using caulk spread across fabric and it seemed like something to add to my long, long “Stuff I want to try to craft” list. I hadn’t gotten around to trying it yet, though, because I expected it would use a lot of flocking material and I wanted to experiment with making some of my own rather than using up my limited supply of the commercial variety.

I’ve also been wanted to do some oceanic or seaside scenery… not for any specific adventure, but just because I like it and wanted to have it around if a use arose.

A few weeks ago, Mel the Terrain Tutor released a video about caulk-and-canvas battle mats which re-sparked my interest in this kind of project. At around the same time a relatively new YouTube channel called Franky D Crafter released a video about making an ocean battle mat. Ocean and home-brew battle mat in one project? Sign me up!

No water required!

I made a Walmart run for the materials I’d need that I didn’t have on hand: a couple of the larger containers of dark blue craft paint ($2.50 each), a few tubes of the cheapest (~2.00 each if I remember correctly) 100% latex caulk they had, and piece of already-cut $2.97-a-yard cheap coarse and relatively heavy-duty fabric. Compared to a 4’x6′ commercial ocean battle mat at around $60, mine would be smaller but still quite a bargain if it worked out.

Many of the videos I watched about this process recommended making a thick mat via multiple layers of caulk, but the Mel and Franky D ones above both went with fairly thin coatings, so I decided to try that first and go the more-caulk route if the less-caulk one didn’t work out.

Opinions also seem to differ about whether to apply the caulk straight and then paint it, or mix the paint into the caulk first and then apply. I chose the latter, reasoning that if the mat got cracked or damaged, it would only expose the base color rather than a streak of bright white.

I put a 40″ or so board – exactly the size of the table I currently play on at home – up on some sawhorses and spread the fabric across that. I pulled it taut without stretching it and put clamps on all four corners to hold it in place.

Too much slime on my hands

I had it in my head that someone, somewhere had said that four tubes of caulk was enough for a mat a little bigger than the one I was making. So I dumped four full tubes into a bucket and started stirring in the dark paint. The caulk sucked up a lot of paint – I ended up using one and a half containers to get to the color shown below. I wanted to go even darker, but I was concerned I’d dilute the caulk to too thin of a consistency.

I started scooping out clumps of the mixture and spreading them across the fabric with a wide putty knife. I tried to texture some arcs into the surface to simulate small waves or ripples in the surface, but I wasn’t thrilled with the results. So I put on a nitrile glove, grabbed a handful of blue goo, and started smearing it by hand! Not only was I able to create a more interesting texture this way, but I was able to spread it faster and more evenly… and it was kind of fun!

The coating even dried darker than when it went on, which was closer to the color I was looking for as the base.

The rippled texture I’d been able to create would be great fodder for dry-brushing.

I did, however, have a lot of caulk mix left over. It turns out I might have been able to get away with using as few as two tubes and a lot less paint. My experiments with the leftovers will be covered in a future post.

Making waves

Mixing the goo and caulking the mat only took about an hour, and could probably go faster if I had to do it again. The longest part of this build was waiting for the caulk to dry! I planned to give it 24 hours but got side-tracked and ended up giving it 48.

Using a big house trim-painting brush I dry-brushed a lighter blue (“Caribbean” craft paint) across the whole mat. Then I added a very light dry-brush of white. It still looked like it needed a little more character, so, taking inspiration from the Franky D video, I dappled on some white to make wave-like arcs that more or less followed some of the arcing textures I’d created. A little more Caribbean was dappled on below the curves to accentuate them a little more.

All that was left from here was to trim off the ragged edges. I used a pencil and a long level to mark just inside where the clamps prevented the caulk from reaching, then cut along the lines with a sharp pair of scissors.

I’ve loosely rolled and unrolled it a few times with no damage to the surface. Obviously I can’t speak to the long-term longevity of it right now – who knows if it will hold up to six months on a shelf without cracking or sticking to itself? But other folks claim to have used this kind of mat for years without problems, so I’m hopeful that it will last. In the meantime it will see some use in an upcoming coastal lighthouse encounter in my campaign.