I know many of you have already gone down the trail of making ground goop in building your layout but I am offering this information for those who have not yet made this jump. Despite the many YouTube videos I have looked at for making ground goop, I never found all the answers for the ground goop application that I needed. My N scale layout is flat foam thus I wanted something to give it some texture and create some variations in the surface. Not trying to create mountains or even hills…..just a small variations to the terrain. I turned to ground goop for my needs. I quickly found recommendations for the Lou Sassi recipe for ground goop so that was my first venture in making goop. The Lou Sassi formula for ground goop is · 1-part Celluclay · 1-part vermiculite (fine grade – found at garden centers) · 3/4-part Elmer’s Glue-All (not school glue) · 1-part flat latex paint · Dash of Lysol (as mold inhibiter) In addition, there are many variations found on internet since this product is used in many different hobby situations – not just model RR. All have good info to offer. My first attempt at ground goop was to follow Lou’s recipe for use in making a small river. Although I liked how it came out, it had some issue that bothered me. · If you get any on a nearby item, the latex paint in the mix will leave a paint smear that is very difficult to remove if you let it dry. · If you have a large area to cover, it can get rather pricy if you used all the ingredients he recommended. As a result, I started looking for alternatives that avoided those issues. (continued in next post)
My first change was to use acrylic hobby paints rather than latex paint. They are typically cheaper per ounce than latex paint plus it is easier to clean off any wayward paint. Note that hobby acrylic paints come in several different types. Some are designed to be more persistent (waterproof, dishwasher safe, etc) so they would be as bad as latex paints in terms of removing errant paint. Read the label. Any brand will work. I chose to focus on the Apple Barrel brand because it was one of the cheaper acrylics out there plus it was readily available at a nearby store. Lou used Celluclay as his base material but I soon found other similar products to try out. Scuptamold is very similar to Celluclay so I got some of that. I also found a product called FiberFusion from Scenic Solutions. It looks just like Celluclay and Scuptamold but has very different properties. Celluclay and Scuptamold have rather short working times but can be stored for a while in an airtight container. It will still firm up over time but can be made workable again by adding water and remixing. FiberFusion has a very long working time, stores even longer in an airtight container plus it can be reconstituted by applying water after it has dried. I really liked the long working time of the FiberFusion and had high hopes for it in my testing. In their raw form, these products are typically mixed with water and then used in a mold, on an armature or free form sculpture. Although they soon become hard when mixed per bag instructions and exposed to air, they were an important element in Lou’s recipe. I wound up using all three products in my testing. My testing included variations of following: · Base material (Scuptamold or Celluclay or FusionFiber). Note that other cheaper materials can be used here but I have not tried them. Some people use chopped up newspaper and I have also seen toilet paper used. Since none of these DIY products include an adhesive, you would need to take that into consideration in your own testing. · Elmer’s Glue-All (not the water-soluble School Glue) · Vermiculite (fine grade) · Acrylic paint (brand/colors of your choice) · Lysol (inhibits mold) Base material: My first round of testing was to compare a mix of the base material, vermiculite and glue using the Lou Sassi recipe. All brands had some type of powered adhesive in them that was water activated. I tried to lay down a thin layer and found little difference between the Celluclay and the Scuptamold. Both allowed me to apply a thin layer but both had a grainy texture due to the vermiculite. I tried to address this in later testing discussed below. The FusionFiber would not work very well at all in my thin/flat testing. FusionFiber is made up with tiny pieces of fabric/thread material that would not break apart into separate fibers when used in a mix. I tried using a mixer as well as running the raw dry material thru a food processer but that did not help. When the mix was applied (thin or thick), the lumpy fibers left the surface with a very bumpy surface. I was very disappointed about this because the FusionFiber mix had a very long working time compared to the others and I really liked that feature. As a result, I decided to restrict the rest of my testing to Celluclay and Scuptamold mixes and reserve my bag of FusionFiber to small hills or other terrain where the lumps were OK. Glue: My next testing was to determine if I really needed the 3/4-part Elmer’s glue. I have seen other variation of ground goop with only a 1/2-part glue. I tested my mix with 3/4-part glue then 1/2-part glue and then with no glue at all. I saw little difference between the 3/4-part glue mixture and the 1/2-part mixture. I also saw that the no glue version seemed to lack the texture to smooth out like I wanted. I needed to lay out thin layers and the no glue version had a problem with that. Apparently, the adhesive powder in the base material was insufficient to make the final mix adhere together very well. I also found that the 1/2-part version would stick to the foam better than the no glue version. I have seen comments where others had problems in this area and they used wall board joint tape on the foam to create a rough surface for the goop to stick to. As a result, I settled on the 1/2-part version in the remaining testing. Paint: As noted earlier, I decided to use hobby acrylic paint in lieu of latex paint. In my initial testing of Lou’s goop, I used 1-part flat latex paint per his recipe. That did a great job of coloring the goop but it also meant that anything the goop touched would get paint on it and would be difficult to clean off. Another benefit of latex is that the paint would hide the vermiculite (shiny chips) very well in the goop. Even if I decided to stay with the latex, I would need to test different amounts of the paint to determine how much paint is really required. I think the 1-part version is more paint than needed and you could cut some cost with less paint. I will note that my earlier use of latex paint made the surface much harder when dry. When I added acrylic paint to my mix, I used considerably less acrylic paint than I did with latex paint. You can vary how much paint you use and it will impact the color. The one issue I have found with hobby acrylic is that it does not have the same hiding ability (pigment density?) as the latex paint. This may not have been an issue if I had used as much acrylic paint as I did with latex paint. Even with lots of acrylic paint in the mix, the shiny faces of the vermiculite can shine through. My solution was to only use as much acrylic paint as needed to get the right color for the mix then come back after it is dry and add paint to the surface as needed. This last step may or may not be needed depending on how you intend to finish the area with rocks/grass/weeds/etc. I will note that I intentionally applied some of the mix with acrylic paint to a piece of Kato Unitrack and was able to clean it off completely 2 days later after it had dried. If that had been a latex paint mix, it would have left some paint stain/residue. Vermiculite: I suspect the vermiculite is in the recipe to make it airier. Otherwise, it would be like working with clay. However, the vermiculite can make the mixture grainy. Note that vermiculite comes in different grades. You will want the “fine” mixture to keep grain to a minimum. My next test was to vary the amount of vermiculite to see what effect that had on the mixture. I tried a 1/4 part and a 1/2 part to compare to the original mixes I made with 1 part. I decided that this is a judgement factor based on what you want the texture to be like. The amount did not seem to modify how well the goop was applied. This surprised me – I expected to see some variation in ease of application. The only variation was how the finished layer looked. I model N scale so any variation in the surface that you do not want can quickly look out of scale. In the end, I felt like the 1-part version I started with had more grain than I preferred. The 1/2 part looked much better while the 1/4 part had very little grainy appearance at all. I decided that the 1/2-part version worked best for me. It had some texture to the surface but not an excessive grainy look. Lysol (or similar): Should be added to inhibit mold. I did not add any for my testing but I will when I use a mix for my layout. Also helps avoid any mold while mix is stored in an airtight container. I understand that it also helps to store the mix in a refrigerator. Water: Need to add water to the mix to get the consistence you want to work with. For my need to spread a thin layer, I tended to make it a bit thinner than might be used elsewhere. If it was too thick/dry, the mix would roll up and not lay down smooth. This is a judgment on your part for your own application. You can play with surface smoothness if you want it ultra-smooth. After you lay it down, let it set for a while and then come back and smooth it some more. I used an artist pallet knife to lay down my layers and it allows me a lot of control. In the end, I settled on the following mix: · 1-part base material (Scuptamold or Celluclay. Both appeared about equal to me) · 1/2-part vermiculite · 1/2-part Elmer’s Glue-All (1/4 part might work also but will reduces how well it sticks to foam.) · 1/4-part hobby acrylic paint (or to your preferences for color) · 1/4-part Lysol (Continued in next post)
This mix fits my need for a colorized ground goop that I can apply in a thin layer that will stick to flat foam for my N scale layout. I will be using this goop in following situations. · Flat or irregular terrain that will receive some type of finish covering (grass, etc) · Fill in space between parallel tracks and in my yard. I am using Kato Unitrack with a raised roadbed for the track. Since the areas between tracks is typically semi level, I will fill in those areas to raise them closer to track bed level and then apply Kato ballast for color and ballast texture. · I do have one small spot where the track will pass beside a small rock face. I want to use some goop to create this area but I will probably need to modify my mix some to do that. I did not test nor try to make a mix that was targeted for steep terrain or a vertical cliff face - may need more glue for that. For HO and larger scale, more vermiculite might work well for you. You will need to do your own testing for your layout situation. My conclusion: · The Lou Sassi ground goop is great stuff but you can adjust the mixture to achieve similar results at a lower cost if that is a consideration. · You can adjust the Sassi mixture to meet different requirements. I suspect it would be a good recipe for using in a thicker application and in mountainous terrain but it was a bit too thick for my need for a thin layer. · Latex or acrylic paint will both work but each has its own pluses and minuses. In my case, the desire to clean off the goop (and paint) from any surfaces it got on in error, made acrylic paint the right choice for me. If you have no such concerns, latex paint works great. · With thin layers of goop over foam like I am doing, any variation of the mixes should work when drilling or punching a hole to plant trees, etc. A thick application may change the game a bit but I think you should be able to deal with any issues even if the surface is really hard. If you have any personal experiences to add, please do.
