Step by step how to make a 3D background

[Steve]

Starting this post because I have a 90g tank for a person that I am about to start building a complete 3D background for today. I know some people have asked how I make them so I figured I'd do a complete step by step with full photos on this build with materials list and tools etc etc to show everyone how it is done. I figure maybe it would perhaps be something we could pin to the DIY forum here so any member that wanted to do one for themselves could have that info on the site?

Will be updating this post starting today as I gather all the materials and start taking pictures/ listing the steps and progress.

[Steve]

Okay here we go.

Step 1...Decide which method you want to go for coating the background. Drylok or cement. I will be using (and suggest to anyone else) to use Drylok for a number of reasons. First off it is MUCH easier to use than cement. It can be applied quickly, in coats with a brush, and does not make anywhere near the mess cement makes. Also since Drylok goes on in thin coats you won't lose the fine details that you will lose when using cement. You don;t want to put hours of work into making a foam background look like the texture of real rock only to have all that detail work wiped out into a smooth thick coat of cement. So for those reasons I suggest Drylok. And as a bonus, Drylok lasts longer than cement in the tank as well. Many people have had cement BG's crack after a couple years, but I have yet to see a Drylok coated BG have issues. My oldest one is now 2 years in the tank and looks just as good today as the day I installed it.

So now that you have chose Drylok you need to get the foam. The only thing to beware off with foam is to realize that "some" foam board contains mildew inhibitors. Normally if it does contain it they will state it right on the foam itself. To avoid the chance simply use the foam board I use from Lowes which is the green board R rated. 1" 4x8ft sheet is only $15, or about $25 for the 2" thick one. For this project I will be using 1" mainly to avoid taking up too much swimming room for the new owners colony of Trophs he will be putting in the 90g tank.

Pics of the Drylok you want and the foam board-




More to come....

[Steve]

Had a bit of actual "work" get in the way for a few days (damn that W- word) but should be back on this Monday and hope to conclude the step by steps and have the finished product with in the next 10 days or so.

[Ron]

No rush - patiently following alone. 

[Steve]

Okay finally got some orders done and out of the way and back on this now.

The next step is to cut a panel of styro to cover the whole back of the tank. Normally depending on the size of the tank (and how many center braces it has) you will have to do it in two or more pieces. Obviously smaller tanks like 10, 20, 29's can be done in one piece which is nice. But larger tanks with a center brace will need to be done in two pieces unless you want to remove the top trim before hand. I have done that as well in the past and that's not a real fun job.

This tank here has an overflow so it will require not only doing the back piece in two sections, but it will also require a little bit more creativity to make it so the overflow housing blends into the background, yet not obstruct the overflow opening. It will be done by butting up the foam tight to the overflow, matching the overflow color to the background color, and then actually siliconing carved out fake rocks to the overflow housing to match the background (but more on that when we get to that step).

For now just focus on getting the back panels cut and dry fitted nice and tight. This seems like an easy step, and it is for the most part, but it is VERY important to make sure you fit it tight against the sides of the tank. If you leaves small gaps then that will create two problems. First one is it leaves an area for small fish like plecos to get into and get wedged, and you don;t want that. Secondly if you have gaps then that creates the need to fill the gaps  with silicone, and drylok/paint will not adhere to silicone very well so you will not be able to hide the gaps properly. So take your time and cut it a little tight the first time, you can always sand the edges to make it fit better.

[Steve]

Now we move onto the part which I myself consider enjoyable. It's the part most people have the most issue with and that is starting the actual design and shape of the 3D rocks. If you're a creative person by nature then this will come some what natural to you. If you're a bit unsure of yourself then spend a little time online looking at 3D backgrounds others have created and then take a few scrap pieces of foam and just start shaping as a bit of practice. Don't be afraid of this part because it's only foam, if you're not happy with a piece then toss it aside and start that piece over. And don;t get too hung up on having to copy an exact example myself or someone else has done. Rocks are a natural material and come in all shapes, sizes and textures so don't be afraid to experiment a bit with your own creativity.

Before we go any further lets talk about silicone. When building a 3d background silicone is basically your "glue" on these projects. You adhere every piece to the background with silicone as well as adhere the background to the tank with silicone. So you want to make sure to get the right one.

You want 100% silicone, and clear. The best thing to use is GE Silicone I* ..it's 100% fish safe (after it cures obviously) very strong for what we are using it for, relatively inexpensive, and easily found at most places such as Lowes, Home Depot, Walmart.



For the design of this one I am going to do an angled rock design. You will simply start by cutting out pieces of foam then using various tools such as knives, scrapers, rasps and files to cut and shape each rock. One thing to try to avoid if to have the rocks goings perfectly horizontal as you apply them. I try to do them on about a 25-30 degree angle because it just adds a bit of focal interest and makes for a more natural looking setting. So start the very first rock in the corner and apply it so the flat top of it is at an angle and this will give you a basic angled guide for the rest of the rocks.

Some of the tools to use


The start of the rocks siliconed onto the backboard and drying. You can start to get an idea of the angle from this one.


At this point you will most likely be wondering about some of the small openings/holes where you can still see the smooth backboard, but don't be concerned too much with that right now yet, we'll cover that later when we get the the final steps with using the heat gun.

[Steve]

Continuing on with the rock shaping, you can see in this current pic how the flow of the rocks at an angle are starting to give it a very natural look such as a sloping underwater ledge that would naturally hold fish. Also it is wise to make one rock higher than the rest every once in a while such as the upright one almost dead center here. That helps to just break up the angle a tad so you don;t have continuous straight lines/levels of rock.

 This rock shaping step is going to be one of the longest steps so just take your time and keep at it. Depending on the size of the tank this step could take anywhere from 3 hours for a 20g, up to 30 hours for a 6ft or larger tank. On this 90g I'll probably have around 20 hrs in just this step.

[Steve]

About 3 more hours this evening now and getting close to having this larger panel done. Then it will be time to move to the 2nd smaller panel as well as the side panels. After than then we will be moving onto the next step which will be giving a bit more texture to the surface of the rocks by use of a heat gun. Still a bit more work on this step though before it's time to move forward.

[Steve]

Next step....

Now we get to the heat gun work. If you notice in the following picture when you have small voids you will see the smooth back panel of foam that the rocks are attached to in some areas, this is fine as it gives a natural look, but what we don't really want is to see the smoothness of the backboard.



So to make it blend in you will just simply take one of your tools (I like a rasp but a screwdriver or any pointed tool will work as well) and just simply rough up the smooth areas a bit



You can see in this pic how it now blends in better with the rest of the rocks



Next is time for some heat gun work. Before you begin this step I highly suggest that you take some scrap foam, rough it up a bit (because roughed up foam reacts differently than smooth foam and melts at a different rate) and then take the gun gun and just get a feel for how quickly the foam shrinks/melts under heat. What you want to do is to quickly pass the heat gun over the background to slightly melt the foam. This is a two fold reason.

First it gives a more natural/realistic texture to the rocks that makes them look more like the real thing. And secondly, after it cools it actually makes the foam a bit harder which in turn helps to make it more durable in the long run. So this is a step that is important for not only looks, but function as well in my opinion so don't skip it.



For comparison you can see in this pic just how different the top half of the background looks which has been hit with the heat gun, compared to the lower half which has yet to be hit with heat



And this larger section of the background is now done with carving and heat gun work and ready to have the first coat of drylok applied to it at this stage. You will probably notice the smooth 3/4" edge to the right side of this piece. That is not a mistake, that is there because I will be building matching 3d side panels to this one and you always want your side panel to butt against the back panel so that the seam is hidden from the straight on view.

[Steve]

In this step you will apply the drylok to the background. A couple of various sized brushes will be all you need. Usually I'll use one small 1" brush for getting into all the crevasses and then a 3" wide brush for doing the larger areas. Two coats of drylok are usually sufficient. The drylok does many things, it somewhat seals up the front foam areas of the background for some durability, plus it gives you a base coat to paint on in the next steps. If you applied paint directly to the foam from an aerosol spray can (which is what we will be doing in the next step) then it would literally eat the foam and melt it away. The coat of drylok serves a number of purposes with one of the most important being that it seals the foam and allows you to paint on it without damaging the foam.

First coat drying overnight and second will be applied in the morning.

[Steve]

Next step is to paint the whole thing black. You will be using a paint that is made for plastics. I prefer Krylon Fusion because I have used it for years now in tanks and know it is 100% fish safe when dry, but there are other brands out there that work as well. I'm just using the larger main piece for this step by step but keep in mind there are actually 5 pieces including the side panels that I am doing this with.

The reason to paint the BG black is because all the rest of the paint work we will be doing is drybrushing work. So when you paint the BG black then drybrush over areas that leaves all the cracks between rocks and low areas a darker color, which is natural looking.

Usually takes two coats of black. This is the first.

[Steve]

This step is where we will add the main color to the background. To simulate the natural color of gray rocks we will use the same gray Drylok, but we will be doing a technique called dry brushing. This is simply  where you will take just the tips of your brush and dip into the Drylok, then take something such as a paper plate and wipe the majority of the Drylok off of the brush leaving just a very small amount on the tips of the brush.
 

The owner of this background whom I am building it for wanted a bit darker rocks so after dry brushing each rock I am taking a cloth and "blotting" the excess Drylok to give it a darker overall appearance. Work this way on each rock, do not try to brush to many at once before you go back and blot them that way it does not dry too much to blot.



Now the main color on this section is done. Next we will be adding other shading to certain areas as well as dry brushing some of the tips/higher points of the rocks with white to simulate parts that have been rubbed clean over time for a more nature look.

[Steve]

Now onto the shading work which is adds the final touch of realism to the background. You will still be using spray cans of krylon fusion or some other plastic paints, but you will actually be brushing it on rather than spraying. To do this simply take a small disposable cup and spray a short burst of paint into the cup, then with a small cheap artist brush flatten out the Bristols and use that to apply the colors. This will be done the same way we did the dry brushing technique with drylok. Dip the tips in the paint and then wipe most of it off on a plate, then lightly drybrush onto the background.



The two main colors that add good "depth" to the background will be a darker brown and then a white. With the darker brown color you want to drybrush the areas where you would normally expect to see mud and silt collect on a rock. So this will be the underside of some of the rocks that stick out more, or any low laying spot on the rocks. After that dries then you will move on to the white highlights on the background. You want to apply the white on the edges and tips of the rocks that would normally show wear in nature. This will be the top parts of rocks, or any part that would stick out or protrude higher than the rest of the rock.

This is a close up so you can see exactly what I am talking about far as where to do the darker as well as the white.



And this is the completed larger section of the background. Only thing left to do on this section is to coat it with Pond Armor pond sealer. I will cover that step after the other four pieces of the background/side panels are ready for sealer. No need to show pics of doing those because they are done the same way as this main piece. Next update will be in a few days when we will apply the sealer and get ready to install in the tank.

[Ron]

How critical is the pond armor? Also, where do you buy it for a good price? When I've looked it up at the local big box stores, it seems rather expensive.  ($80 for 1.5qt IIRC).

[Steve]

It depends on if you have plecos in the tank Ron. If you don't have or don't plan in the future to ever have plecos in the tank then you don't actually "need" pond armor sealer. My very first background I did without sealer is still going strong (3 yrs now) and still looks good. Now if you have or will ever have plecos in the tank, then pond armor is 100% critical to use because they will end up rasping on the background and over time you will get spots where the foam underneath the drylok will be exposed.

Far as price of the pond armor you are dead on with what you saw, it's not cheap by any means. Cheapest place I have found is Amazon where I got mine and it was $78 for 1.5Q (it's a 2:1 mix). One thing I do is to thin mine with a bit of denatured alcohol and that makes it last longer. I'll cover the mix and thinning etc etc in the next step for everyone.