I’m in the process of building my first ever water feature and would like your suggestions as to how to seal the ponds bottom in preparation for using whichever ‘water’ I’ll eventually pour. In this particular area of my layout there is a section of 3/16ths sheet cork laid over and glued to blue foam board. I’ve cut away the cork in the shape of the pond (see photo below)
I know that I have to seal the edge where cork meets foam on the ‘banks’ and also the entire pond bottom since this spot is where a couple of sections of foam meet under the cork. What is the best method for doing this? Do I use plaster cloth or what? What did you do to get that water tight seal on your water feature?
Jarrell, I lay plaster cloth over the bottom first, then I spread sculptamold over that and let dry. I paint and scenic the bottom next before pouring the water. Seems to work for me Dave
Hi Jarrell: I also used plaster cloth, covered with that pink spackle that turns white when its dry. That’s going to be a great looking pond when finished. DJ.
I had had good results simply damming up the sides with duct tape or the green painters’ masking tape, and then pouring maybe 1 full cup of mixed plaster of paris or hydrocal (your choice) and painting the top of the prepared lake bed to that point. The idea is to keep working the still goopy plaster up the sides of the ‘vessel’ until it wants to stay. Hyrdrocal is probably a bit better in the ‘until it wants to stay’ part because it sets up a bit earlier than will the PoP.
In your case, I would dam with some putty first to provide an early surface rising from the bed to the bank tops. Wood putty should be fine. Actually, so would latex caulk if you don’t mind running a wetted thumb along the bank to shape the dam. Or use a trowel or something.
When the putty has dried, or even fairly well set but not quite dry, you can go ahead and add a layer of the plaster or hydrocal. When it is hard and dry, maybe overnight, then paint the central portion black and then fade toward the banks with a bit of green. Then, pour your water substance.
In the case of my girder over the water you know, Jarrell, I gouged out the surface of extruded foam to create a shallow cavity. I lined it directly with PoP, but I also inserted some pebbles into the still-wet plaster so that I had a boulder river bed. I also added some trimmed twigs that I had pre-painted to look weathered out of the ‘water’, and I stuck them at shallow angles into the plaster. I think I also sprinkled some dirt over the bed to give it the right colour once the epoxy was poured. It looked natural except for the glassy water surface, and I eventually changed that.
Plaster cloth would certainly work, although you would have to apply it several times to layer it and to seal it against leakage of the water.
Thanks for the replies everyone. I have a question about using spackle, hydrocal etc over the plaster cloth, does it have to be sanded smooth before you go to the next step or is that necessary?
If your base is pink/blue foam, you don’t really need to worry about sealing the bottom if there are no seams in your base below it. Envirotex Lite, at least, will not react with the foam.
That said, I used plaster cloth to make a more “presentable” bed for my ponds. I coated that with Gypsolite, which I like for its gritty texture, and sealed the nooks and crannies where the plaster cloth showed through with Elmers, full-strength. Then I painted the pond bed with acrylic craft paint.
I think it’s important to pour multiple layers of “water,” and to tint each layer slightly. This adds “optical depth” to the water, and gets rid of the “clear as glass” look. The lower layers can be dark, almost murky, and the upper layers almost clear.
Don’t be afraid to waste a bit of “water” with test pours into plastic cups with different tints. It gave me a lot more confidence when I went for the real pours on the layout.
I would urge you to take this advice, Jarrell. It will be quick to make a simple test bed and paint it, and then fiddle with mixes and finishes to see if you like how it ends up. Then, armed with a recipe, you know you’ll have the look you want permenently.
If applied as a rather soupy, self-leveling mixture, hydrocal/plaster doesn’t need any further attention, Jarrell. In the case of spackling compound, the final surface before making the “water” pour simply shouldn’t look distinctly rough, or it will be apparent through the “water” later on and might look odd.
Thanks for all the advice, and I think I will do a ‘test’ pond first. I have some 1/8th inch hardboard and it won’t be difficult to make a small pond by glueing a piece that is cut to the shape of a pond to a bottom piece.
