Failure in a Box
I call this failure in a box for reasons that will become clear. My original concept was a sunken treasure diorama hidden in a treasure chest.

The box

I planned to use spray foam to create the rocky underwater area. However I did not realize that the spray foam that I bought does not harden when it dries. It stays flexible therefore did not create the rock look I wanted. I had already sprayed it in the box, so no turning back. I painted and did a green wash over the foam. Because I planned to use clear resin for water I checked to see if the foam I used is chemical resistant. I found nothing on the can indicating as such. In order to seal the foam I decided to coat everything in clear caulking. I then built a partial ship hull out of balsa wood and test fit it.

unfinished hull in foamed box

As you can see I don't have a ton of WIP pics so some steps may be combined in one pic. For example this next section.

I created a mixture of school glue / white glue, or whatever you call it with water. I didn't measure exactly I just added water until it was suitable to brush on. I brushed the glue water mixture in the area I wanted to be sandy. Then I dumped sand on top of the glue. Also in the next picture you will see the stained, and broken hull with a treasure chest in the break.

hull in the sand

I also added a few small plants. The plants were mostly made from small pieces of artificial plants. The mast is wooden doweling. In the corner there is a fishing net made of tulle. The pirate flag is hand made by cutting out a paper towel and then painting the skull and crossbones.

top view

So as I said, I assumed I had everything sealed up and mixed and poured the resin. After a short amount of time it became obvious that the rosin was leaking through the scenery and into the box. As a result the resin ended up being too shallow

shallow view 1
shallow view2
shallow view 3

I have plans to re-make this properly. I also intend to have a talking skull in the lid that will say dead men tell no tails when you open it.


When I do the real thing I will have more of a proper WIP post. 
Oh, man. Such a cool concept, it's a bummer that the resin didn't cooperate.  Sad
An ambitious project that sadly went awry. I have a few observations.

As you discovered, spray foam skins over, but never fully hardens. It is good for filling voids, but since you cannot carve it, does not make a good final surface. Foam insulation board would have been a better choice here, you would have had more control of your shapes. But no matter what type of foam you use, know that they do not play well with resin. It dissolves foam on contact. You would have to completely seal the foam first, and there are few enough products safe for foam that themselves would resist resin. Ableman33 on this forum seals his foam with a mixture of Elmer's and water, but that is partially so he can use spray paints that would otherwise be damaging. Possibly several coats of this mixture may produce a barrier that would keep the resin away, but all it would take is just one small pin hole for the resin to destroy the foam. I believe this has happened to you. You probably have a cavity filled with resin on the bottom of the chest, and it wouldn't surprise me that it has not cured, and possibly won't cure. You may have  terrible mess on your hands, and I hope the chest has not been ruined.

There are things to consider about resin. One of the most important is it should be spread in thin layers (usually an eighth of an inch, but never more than a quarter inch), and allowed to cure before adding more layers. Trying to pour thicker amounts can cause the resin to distort and ripple, or not cure completely. There is also the consideration of bubbles, you will have no chance of removing the deeper ones. And most resins produce heat, enough to burn skin. The thicker the pour, the greater the heat. Even if you sealed the foam properly, the heat will probably do damage. And lastly, resin that thick may not be transparent enough to give you the effect you desire.

Now, maybe you are using a newer resin that is not so problematic as the resin I am describing. I know Woodland Scenics is producing a new line of water products, and maybe they have one that will allow deeper pours.

..............why bother with the mess of resin at all?

You will be looking straight down into the chest, with no side view at all. Get a piece of clear glass cut to size, and place it where you want the surface of the water to be. You can lightly paint the underside around the edges with blue, green, or turquoise, to give you a depth effect. WS has had a water effects gel for years that you can sculpt into waves on the surface. It dries clear, then you can paint white caps on it. You can even paint the white caps directly on the glass. The nice thing is if you don't like how it turns out, you can scrape it off with a razor blade and start again. And it allows you to rework the bottom scene whenever you want.

I look forward to seeing you bring this project to fruition.

Thanks for your observations and suggestions. However the spray foam that I intended to use is called Great Stuff and it does in fact cure hard and can be carved, filed, sanded, and shaped the same way foam board is. I didn't buy great stuff because I was in a hurry at Home Depot so I grabbed the first can of spray foam, which unfortunately didn't dry rigid like the Great Stuff foam. I am very well aware of the effects of chemicals on foam as I have worked with it quite a bit. Clear caulking has worked for me in the past as a sealant against resin. However as you pointed out. There were obviously gaps in the coverage.

As far as using resin. I have not had a problem when pouring in mass quantities. It has always cured all the way through due to it curing by a chemical reaction. The only thing to beware of is the heat it generates.

As far as rippling and air bubbles, those are the specific characteristics I like about the resin. There is a definite difference between looking through a flat piece of glass and looking through resin. The ripples in resin and the bubbles I feel are a much more realistic representation of water.

I do appreciate your suggestions and acknowledge that every terrain artist has their own opinions and preferred techniques.
[+] 1 user Likes locomoticopter's post
Okay, so this is not your first resin rodeo. Wink  I look forward to seeing lots of WIP shots. I'm always ready to see new techniques.

Don I want to let you know I was neither offended nor did I intend to offend. I just wanted to clarify a few things.
I wasn't offended either. Most of what I know I've learned from reading hobby magazines for the last 50 years, and many of those procedures I actually haven't done myself, like resin. I'm always ready to hear something new. Several members of the previous incarnation of TerraGenesis did remarkable things with cardboard, a material I did not really use other than to make templates (I prefer to use styrene), but now I find it relaxing to play with. So I honestly do want to see how you complete your scene.


I should clarify, I have never poured resin to make water features, but I have made rubber molds, and cast with colored resin.

Forum Jump: