N:AW Ash Wastes Game Mat

So something that you need for a Necromunda Ash Wastes (N:AW) game is in fact "ash wastes", that is a playing surface.  Your usual green felt or shattered future city is not really applicable.  N:AW has effectively two game scales, one which is the usual Necromunda scale skirmish, which you play on a 3x3 foot or 4x4 foot board, and "rolling roads" where there is some sort of vehicular chase/heist/etc. which needs a 6x4 foot or two boards that you switch to represent the road passing by. The boxed set came with a rather nice 3x3 foot printed paper mat, which has a day and night side, but it is glossy and already showing a bit of wear at the folds.  So the idea came to make a new game mat to represent this surface, and more to make it from a new technique. [who would be smart enough to use a tried and true technique?]

Googling around for various ash wastes mats, I somehow came across this video from Black Magic Craft.  He has a few more videos that use this same technique to make roads and rivers, which might have been where I found it the first time. 

I really liked how it seemed heavy and dense compared to caulked canvas, and the idea of using rollers and other things to mark the caulk seemed like a good one.  So after some research, I found a similar runner from Lowes (the same product as the video is not sold at Home Depot in the US), bought some caulk, and got to work.  

So to learn how to make one, continue after the jump. 

Materials needed:

    3x3 foot segment of Vinyl utility runner (or any length you like) 
    2 tubes of grey Dap Dynaflex Ultra (highly flexible silicon/acrylic caulk)
    Sand/Flock/static grass etc. 
    Paint

Tools needed:
    Long metal ruler
    Utility knife
    Caulk gun
    Wide putty knife
    Sponge
    4 inch roller
    Small bucket of soapy water
    Drop cloth (here plastic sheet)

Safety gear:
    Couple pairs of disposable gloves
    Outside air

Waste generated: 
    Gloves
    Empty caulk tube(s)
    Drop cloth (do not cut on the drop cloth!)

Method:

Here is the runner, you can see it is a few mm thick, and has two different textures

Supplies

Take the roll of rubber non-slip runner, and trim it to the correct size.  The adage "measure twice and cut once" is important to remember here, unless you have a rubber non-slip runner stretcher on hand.  Consequently my desired 35.5x35.5 inch mat became a 35.5x34.25 inch mat. In my case, I also bought a 4 foot length, which became a 50 inch length under the "skilled" cutting of the Lowes employee.  I thus have approximately 14 inches by 3 feet remaining, which will likely become roads and such. 

After the mat is ready for the caulk, use the caulk gun to spread it out evenly.  For 3x3 feet, I used approximately 1.75 tubes, but your amount may vary depending on how thick you want the surface to be.  Then take your putty knife, wet it with the soapy water and smooth out the caulk, taking care to avoid knife marks as you get closer to "finished".  In my case, I deliberate left some square areas about a knife width to be sort of concrete pads.  You might want to build these up to sit "above" the rest of the mat.  Correspondingly, you may want to scrape down through the caulk to the mat surface to represent slightly sunken roads, rivers, or craters. 

Basic surface covered

Once you are satisfied with the caulk surface, it is time to add to the texture through use of the sand and other items.  In my case I used sand, railroad talus, coffee grounds, some flock and a lot of baking soda.  Think about what you want your surface to look like, since perhaps you want the sand in ridges, or the live materials to be clustered together and so on.  

Once you are generally satisfied with the placement, use your gloved hand, a clean putty knife, or a spent caulk tube to press the material a bit into the caulk.  You may want to add more material as you go.  You can also use various techniques to press the surface with patterns or a sharp edge to draw in the caulk. I added a few expansion joints to the "concrete" slabs.  I then went over the surface with a wet sponge, which completely removed the knife marks, and mixed things up in a more natural pattern. 

The fans probably were not necessary

Once you are done decorating the caulk, leave it to dry for a couple of hours.  In Sacramento it was a normal summer day of 90 degrees F [32C], and under 35% humidity, so everything dried quickly, except where the caulk touched the plastic drop cloth, so I moved the mat to a new section of drop cloth and gave it another 30 minutes.  Once everything is dry, you can paint it.  I used a small roller with a foam roller pad, but a larger one would work as well.  Depending on your end terrain goal, you will have different colors to use, but generally you want an all over coat of "dark" and then a more splotchy coat of at least two different "light" colors. When you are satisfied, leave this to dry. 

Once the base paint is dry, you should determine if the surface texture is sufficiently adhered or not.  Since I was a bit hasty in my "pressing" stage, I still had some loose material. I gave the whole board a thin coat of diluted PVA glue which I sprayed on and then rolled out until it was evenly covering the board. 

Once THAT is dry, then dry brush the surface, work on any details you may want to add, such as puddles or oil stains.  I used a 2 inch brush for the first two coats of dry brushing, and then a similar sized makeup brush for the final light dry brush.  As usual for this sort of dry brushing, you want to start darker and work your way up.  I used a fairly heavy ochre dry brush, ochre plus white, and then mostly white, but you may have other colors in mind.  At this point you can either call it good, or depending on your interpretation of "ash wastes" add some more tufts and the like.  In my case, I left it pretty generic, figuring that everything in this area is fairly dead. 

And here is the final product! 

Lessons learned: Measure twice, cut once. Baking soda is pretty good on spray painted bases, less good on this surface where I was rolling wet paint on, and most of it came off reducing the look I was going for.  Trim the edges before painting to save time (and I still need to do that). 

Here it is in action: