Chipped Paint Material
By Neil Blevins
Created On: June 11th 2009
Updated On: Jan 2nd 2010

Go here to read this tutorial in Russian.

The following is a recipe for a chipped paint material. Old paint tends to flake off, or gets chipped off by blunt objects hitting it. Adding a little chipping to the paint in your model can add a lot of realism, and gives your objects a sense of history. Afterall, it's not just the dialog that provides the story, but every detail on every object. Chipped paint lets the audience immediately know how old the object is, or how often it's been used. I will use 3dsmax for this example, but as always the theory works in any 3d app.

The basic ingredients for the material are as follows:

Check out these 3 photos. The first is some nice patterns of paint chipped off a radio antenna.



Here's some paint flaking off a fire hydrant, notice that the paint flakes off to reveal an undercoating of other paint.



And here's a nice image showing the bulging that occurs around the areas where the paint flakes off.



Composite Material

The first thing I do is set up a Composite Material (you can also use a set of blends) so we can layer a bunch of other materials together. The lowest layer is a Base material, Mat 1 is the UnderPaint material, Mat 2 is the Paint Layer.



Base Layer

The base layer is just a grey diffuse, feel free to spruce this up to look like metal for example.



Underpaint Layer

The color of the underpaint material will be a slightly yellowish white.

Now lets work on the chipped paint pattern. In a new material editor slot, create a mix. This pattern will be made up of two noises, masking each other. The first noise looks like this...





The second noise looks like this...





Combined, they form this pattern...





Here's the pattern on our test object.



Next we're going to clamp this noise to make a sharper edge. First, you'll need the free plugin ColorCorrect, which is available here. In the opacity of your underpaint material, place the ColorCorrect map. In the Source map slot, place the "ChippedPattern" from above. Then set the Clamp to 0.5 and 0.7, and check "Normalize".



This is the result you get...



If you don't want to use the ColorCorrect plugin, you can also do something similar with an Output map with it's Color Map adjusted. First, in the opacity of your underpaint material, place an Output map. In the Map: slot, place the "ChippedPattern" from above. Then check "Enable Color Map" and modify your Color Map Graph to look like the graph below...



This will give you the same results as the ColorCorrect example above, personally I just prefer the ColorCorrect method because I need to click less buttons to get my result.

Paint Layer

Now the paint layer. Add a slight specular highlight to your paint.



For the color, add a yellowish color (or whatever color you want your paint to be).



In the Opacity slot place a new ColorCorrect, add the original Chipped Paint pattern to the Source slot, and set the Clamp to a value of 0.7 and 0.9, and hit normalize.



Or if you want to use the Output map method, in the opacity slot place a new Output map. In the Map: slot, place the "ChippedPattern" from above. Then check "Enable Color Map" and modify your Color Map Graph like this...



Here's the result showing all 3 materials layered together.



So here's the reason for the two ColorCorrects (or two Output maps). You want a hole that goes through both the paint and underpaint layer revealing the base layer. However, the paint layer would chip off first, followed by the underpaint layer. So you want to see a little bit of the underpaint layer at the edges of the holes in the paint layer. So by using 2 ColorCorrects and clamping their values a little differently, you pull a little of the white material into the chipped areas.



This is even more apparent when you have a darker paint color.

Ok, now lets add the bump. The bump will be a mixture of your "ChippedPattern" map, and a brushed paint texture I created by scanning real acrylic brush strokes...



I apply this brush stroke texture using my Blended Box Map Technique.

I mix the two together to get my bump.



Here's what the bump itself looks like on the teapot, you can see both the brushed texture and the bulging around the chipped paint pattern.



And here's the final result...



Here's the max file. Requires Max 8 or higher, and the ColorCorrect plugin mentioned above.


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