I tried to lay down some ground cover on a small demonstration module that a group was working on and things didn’t go well. Perhaps someone can offer some suggestions for “better luck, next time.”
The module was made with pink foam glued onto plywood; it’s plenty strong so I can’t see that as an issue. Some areas were also covered with plaster cloth. The foam/plaster cloth was painted with a flat, acrylic craft paint and allowed to thoroughly dry (2 weeks). We tried to affix ground foam to the pink foam with Elmer’s Glue diluted about 1:1 with water. The glue was generously applied in an area about 6"x6" then liberally covered with ground foam. This was allowed to dry for an hour.
When I used a small vac to remove the excess foam, much of it came off in clumps. The glue underneath was totally dry; it appeared as though the ground foam was totally unaffected by the glue.
Using a similar application technique with colored sawdust instead of the ground foam worked very well so I suspect that there is something about the ground foam that the glue doesn’t like.
Painting on glue and then sprinkling scenic material over it is a good first step, but it’s not going to hold very well for anything but the finest-grained materials. That might explain why sawdust worked but ground foam did not.
I generally paint on glue and apply turf and fine stuff. Then, I add the ground foam. Next, I use a pipette to apply isopropyl alcohol straight from the bottle, and finally a thinned-down mix of white glue, 1 part glue to 3 parts water. The alcohol is a “wetting agent,” and helps the glue mixture flow and saturate the scenic materials. Use lots of glue. If the technique sounds familiar, it’s exactly like ballasting.
Your scenery may have seemed dry after an hour, but it really wasn’t. I give mine 24 hours, at least, and more if it’s humid and it’s slow to dry. The alcohol will also speed the drying process, another reason to use that instead of the more traditional dish-soap-in-water mix.
When I apply ground foam on pink or blue foam board, I paint the foam board an earth color first, and before the paint dries I sprinkle the first layer of ground foam on the wet paint. after that dries I then go ahead an fallow Mr. Beasley’ s way with the next two or three layers.
For the first “coat” I wouldn’t dilute the glue, brush it on full strength. Then as noted go back with a little wet water (water with a little alcohol or dish soap) and then add diluted white glue or matte medium.
Unless your landforms are quite steep, simply apply the scenic material (foam, ballast, sawdust) dry, and arrange it, where necessary, with a soft brush. Next, fill a good-quality sprayer with water and add a couple drops of liquid dish detergent. This is what’s known as “wet” water, and it is the key ingredient needed to allow the glue to bond the scenic materials in place. If your water is especially hard, some folks suggest adding alcohol. Mist the water onto the scenicked area, aiming the first sprays upward and letting the mist drop. This prevents the light material from being blown away. Once the area has been dampened, you can spray it directly. Continue spraying until all of the scenic material is wet right through. Next, use an applicator bottle to apply a 50/50 mixture of white glue and water - anything that allows you to control the flow of droplets will work. Saturate the area - the thicker the layers of foam/ballast/sawdust, the more glue is required.
I use this small plastic bottle which dispenses the thinned glue in drops - a little squeeze increases the rate, when necessary:
Do not touch the area while it’s wet. When all areas have been treated, walk away for a day or two, or, where the material is especially deep, for a week-or-so.
On areas where the slope of the land is steep, paint the white glue on full-strength, sprinkle on some scenic material, then lightly mist the area with the “wet” water. This will draw some of the glue up into the loose material. Once this has dried, you can go over this area again, applying more dry material, spraying with water, and adding the thinned glue to achieve the look you’re after.
Generally, when ballasting track, I like to apply the lineside ground cover in the same operation. This saves time and glue, too,
Use a wetting agent first, preferably 70% rubbing alochol, which should be sprayed on. Then, a 1:1 solution of white glue and water is fine, but wait at least 24 hours, better yet 48 hours, or to be sure, do what I do and wait 72 hours.
Sprinkle or pour some ground foam into the index card.
Gently, and I mean gently blow the foam into the wet glue.
To aid in saturating the foam into the glue, I use a garden mister (they seem to have the finest mist), and spray the foam just enough to wet it. It will help wick the glue into the foam.
For really steep scenery bases, use the same method that I use to apply the foam to apply sand. When this dries, it give the area some “tooth” to help hold the ground foam. Then, I repeat steps 1-5 to apply the ground foam
And, as been mentioned, give the glue a good 24 hours to dry completely.
First I just have to ask…why did you let the paint dry for two weeks, but the glue only an hour? Acrylic Paint drys quicker by nature than glue. I think only allowing the glue to dry for 1 hour before applying major suction was a mistake.
Second, I would paint on glue to the substraight.
Third< I would then sprinkle on the ground foam and other scenery bits, and I would use “wet water”, that is, water with either a drop of dish detergent or a few drops of rubbing alcohol to “wet the scenery” as you apply it to make it take stick better.
Fourth, I would then mist or use a squirt bottle drop by drop with the white glue/water mixture, or some folks like Matte Medium as a “glue”.
Then ALLOW IT TO DRY thoroughly before trying to vaccuum up. I mean a few days, more if humid where the layout is located.
WHen you DO vaccuum, place a lady’s stocking over the end of the hose/tube and allow some of it to retreat into the hose/tube. It will collect the extra bits that may not have “glued” very well. That way you don;t “waste” any or get them dirty so they can’t be used again.
Sounds complicated, but the results will be worth it. The KEY is the “wet water” which loosens the nature adhesion tension of the water to resilt the glue and ground cover. The Second KEY is to allow to DRY thoroughly.
You can speed up the drying time by using a fan pointed at the area. keep the fan at least 4-6 feet away so it doesn’t blow the material away. This can shorten the drying time to 3-6 hours depending on saturated the ground was. I did this all the time when I was scenicing layouts at a layout builder I used to work for.
From your description, ir sounds like the ground foam acted like a flock of miniature sponges. This would explain why the glue appeared to be “dry” when you vaccuumed it after only an hour. Elmer’s type glues will have a fairly quick, strong hold between surfaces that have fibers or are very porous-such as the sawdust to plaster cloth application. This is mostly because the fibers are softened by the glue/water mix. Foam does not soften, it merely absorbs the glue/water mix. What you really want is for the glue to form a strong film wrapped around part of each piece of ground foam and into the top of the plaster cloth. Often I will “paint” the top layer of a plaster surface with a 1:1 glue/water mix and let it dry thoroughly before painting or adding scenery materials, because this technique holds paint up on the surface of the plaster better. It also anchors the glue that holds foam/sawdust/plant materials etc. more strongly to the layout.
My technique is to paint the area with a flat latex paint.
While the paint is wet, sprinkle ground foam on the wet paint.
When the paint is dry, add more foam as required.
Dribble a 50-50 glue-water mix over the foam. Let that dry overnight.
Test how secure the foam is. Add additional foam as required.
Re-apply the glue-water mix. Let that dry overnight.
Then vaccuum.
Scenery I have secured by this method has survived riding in an open pick up truck bed, driving at 75 mph down an interstate highway without blowing off.
