Does anyone know of a way to estimate the amount of water-like material one might need to fill a layout bay or river? It seems to me that not having enough when one starts a project is worse than having too much. To keep the cost down, knowing this would be of great help. Thanks.
First, take the area of your body of water. If it’s a circular pond with a diameter D inches, find the radius by dividing D by 2, square the radius and multiply by pi (3.14 is close enough.) If it’s a river L inches long by W inches wide, multiply L by W. Either of these will give you the area in square inches. Then, multiply by the depth and you will have the volume in cubic inches.
But, my water is made of Envirotex Lite, which is sold in fluid ounces Multiply the number of cubic inches by the conversion factor 0.55 to get the number of fluid ounces you will need.
Next, go to www.michaels.com or www.acmoore.com, the web sites for those art supply companies. Find the weekly coupon good for 40% off of one item and print it out. Take the price of the Envirotex, multiply by 0.4, and find out how much money you’ll save.
This is a very good question and the more realistic and irregular your riverbed, pond or other body of water is made to be, the more difficult it is for pure math solutions to really nail it down.
When I faced this particular issue for a major creek bed I “cheated” in a sense, because I also had two other smaller projects (trackside ditches) that were ready to go and one or both could have absorbed excess material, had there been any. As it was I guessed it just about perfectly.
I suppose you could fill the pond or riverbed or whatever with fine sand and try to get a visual as to how much of a cup or other vessel is used up. Then vaccum up the sand (perhaps in a way so it can be saved or re-used).
Another thought would be to press a sheet of aluminum foil into your pond or riverbed, make an exact impression of the area, carefully remove the foil impression, and then rest it in a series of towels or cloths so it holds it shape and can handle the weight of water poured into it. Then see how much water it takes to fill up that area. I suppose you could even pour the water with the foil in place but you risk wetting the actual area on the layout and have to find a way to get the water out (turkey baster?).
But in my experience unless the project is very large, guesswork gets you pretty darn close.
Dave Nelson
An important detail is how deep the material needs to be. On my grandson’s layout our first pond (the void created with using arouter on the plywood) was a failure because I assumed it needed to be deeper than needed (with painted bottom, etc) and I poured in 2 layers (batches) instead of one larger pour. I used the Woodland Scenics meltable plastic beads. Th result was a pond that later cracked into several large pieces with (in the home) temperature variations, most likely due to the multiple pours. Anyway, a second one worked (and looked) fine with one pour and much thinner layer of product. I dont’ know the best thickness for various materials that can be used, but others may know.
The first pond was covered over and now is a Cornerstone “skyscraper construction site”.
For poured ‘water’, you should use two or three layers where you pour about 1/8" thick each time and allow the first layer to cure for at least 24 hours. Also, they should be covered with a clean cover that will reduce dust from moving air from accumulating on, and marring, the surface.
The best way to estimate, also because it is quick, is to generalize the surface to be covered into the shape of a circle. This is an intuitive process, and there will probably be an error. However, a too-thin layer or a sllightly too-thick one is not going to be problematic unless you have a rather gross estimation error, and that would come from bad calculations or a poor substitution of a suitable circle.
Look at the general surface area, measure across it in three or four places and at different angles, and take an average of all measurements. That is the diameter of your ‘circle’. If you have significant protrusions, or ‘arms’ of the water body that are not included, add an estimation of the surface area to your circle’s area. Then, once you are happy with the area estimate, use the formula for the volume in a cylinder.
- Cubic Volume
V = π×r²×h = π×D²×h ⁄ 4
Just use the right units of volume, ones that you can work with when measuring the v
Y’know what? You can’t buy 9.37 fluid ounces of Envirotex. Your choices are 16 and 32. For other products, there’s only one size.
I did my first model water about 4 years ago. I didn’t know how much to buy, either. So, I printed out the coupon and got a large Envirotex Lite, 32 ounces. It was too much for the project, so I cleaned off the tops of the bottles really well, put the caps back on and put it on a shelf. I’ve opened it up and done several different projects, large and small, since then. I’ve gone through about 3/4 of it, and it still works fine. So, shelf life does not appear to be a problem. Too much? No problem. It keeps well, and you’ll have it for later projects.
Or, you can buy the smaller size. Envirotex will give the best results if you pour several thin layers, as mentioned earlier. Between layers, you want to wait 24-48 hours to let the lower layer fully cure before adding more. If you run out, you’ll have plenty of time to get more. Too little? No problem. They’ll make more.
How does one print out a coupon?
Find retailer’s website, find the offer, open the page with the coupon, look for “print” or “print coupon”, and click on it.
In my opinion, many modellers end-up using too much water-making product simply because they attempt to model deep water when they need only represent deep water. Like much in our hobby, a well-done representation can be as effective, or even moreso, than modelling it in-full.
Wayne
Thanks, Selector.
www.michaels.com or www.acmoore.com are the ones I use. We have both of these stores close by. They honor each other’s coupons, too. There is pretty much always a “40% off one item” coupon.
These arts and crafts stores are great. You probably don’t want a pink pony pillow, but they stock balsa wood, razor saws, acrylic paint, brushes, Envirotex, plaster cloth, foam board and other stuff we use in our hobby.
Smooth-on is a web site that sells casting supplies. They have a calculator that will give you an estimate of the amount of material that you will need for a project. I have used it for resin casting, but I don’t see why it couldn’t be used to get the volume of material needed for model RR water.
I agree. Create depth with the color painted under the “water” not by making the resin itself deeper. I don’t think any of my water is deeper than 1/8" save one mistake. The mistake was in the mixture of the resin so it didn’t harden. I had to pour a 2nd layer over the top just to get a hard surface. I think that river is now 3/16" to 1/4" thick.
Yes, as in break out the calculus books. Instead, approximate the area by “overlaying” it with imaginary smaller rectangles and add their area together. Kind of like digital music.
A final side note. If pouring over a foam base make certain there are no cracks in the paint. I had a river where I had used a pin to hold a few reeds in place. The resin found the pin hole, found the foam under and dissolved itself a new cavern out the bottom. I couldn’t figure out why after pouring the resin in there wasn’t enough. Then I found the “lake” on the floor.
Thanks to all of you and your input. Envirotex it is, I will make sure the plywood base is leakproof, and I will just spring for a quart and save the rest.
Thanks again, you all have been very helpful