How to Make Concrete Color Samples

Making colored concrete can be accomplished either by adding pigments directly to the concrete mix before casting or staining the concrete once it’s been placed. In this guide we’re going to take a close look at how to create custom colors for adding to the concrete mix prior to placement. The concrete is often referred to as “integral colored concrete” with uniform distribution of pigment throughout the entire batch of concrete.

While the pigments you choose are very important when formulating a color, many people are surprised to learn that the colors of the cements, additives, and cement replacements are equally important. Portland cement is available in both grey and white version but only the white portland cement must meet strict color standards. The grey variety can range from warm taupe to cool grey or even green. For this reason, making a custom color sample is not as simple as recording a few pigment names and proportions. You need to keep detail notes that record the concrete mix you’re using. If you’re making a mix from scratch keep track of all the materials including cement, aggregates, admixtures and cement replacements like fly-ash or csa.

What You’ll Need To Make Concrete Color Samples
  • Rubber Mold or Sample Form
  • Scale
  • Mixing Buckets
  • CHENG Countertop Pro-Formula Mix
  • CHENG SmartColor Pigment
  • Concrete Mix

Step 1 – Make a Sample Mold

Creating Custom Color Samples - Step 1 | CHENG Concrete Exchange
  • Choose a manageable size. The samples used in this guide are 4″x6″x3/4″
  • Making a rubber mold is one way to save time and produce multiple samples.
  • Using a similar material to the actual formwork of the project will help ensure the sample accurately reflects the finished product.
  • Refer to the Mixing Rubber and Casting Rubber Guides for tips on creating your own sample molds.

Step 2 – Custom Color Formulation

Creating Custom Color Samples - Step 2 | CHENG Concrete Exchange
  • When creating custom colors, be extremely thorough and take notes on the proportions, temperature, time curing, and any other factors that will make it easier to match the color in the future.
  • Assigning a color code to the sample and keeping the details in a spreadsheet is one way to manage a range of samples.
  • Refer to the Calculating Color Formulations and Pigment Loading Guide for more detailed information.

Step 3 – Mixing the Color

Creating Custom Color Samples - Step 3 | CHENG Concrete Exchange
  • Record the exact steps used in custom color formulation and mixing.
  • Be precise when creating the color, even a small variation will change the finished color when mixing up a larger batch.

Step 4 – Pour and Vibrate Concrete

Creating Custom Color Samples - Step 4 | CHENG Concrete Exchange
  • Recording any details of the casting process, such as mold release used, temperature, humidity, how long the piece was vibrated, etc. will help you replicate the color and finish again.

Step 5 – Taped Notes

Creating Custom Color Samples - Step 5 | CHENG Concrete Exchange
  • If you’re pouring multiple samples at the same time, make notes on a piece of tape so you don’t get confused a few days later after the pieces have cured.

Step 6 – Cure and Demold

Creating Custom Color Samples - Step 6 | CHENG Concrete Exchange
  • After the pieces have cured, transfer the notes from the tape to the back of the sample pieces.

Step 7 – Polishing

Creating Custom Color Samples - Step 7 | CHENG Concrete Exchange
  • Having different colors is just one part to building a library of samples.
  • Polishing a sample to expose the aggregate will give the piece a very different look.

Step 8 – Library of Color Samples

Creating Custom Color Samples - Step 8 | CHENG Concrete Exchange
  • Having a selection of samples to show clients is a great way to help them decide on a texture, color, and finish.

If you’re grinding the surface of the concrete the aggregate will also be an important consideration. As soon as you start grinding into the concrete you’ll expose the fine sand and then the rock aggregates. The aggregate in your concrete will vary depending on the geology of that region. If you’re planning to grind and polish your work, choose a color that looks nice with the aggregate in your area. (Charcoal concrete with white limestone aggregate doesn’t look that nice.)

There are two common types of pigments used in concrete, synthetic oxides and organics. Both are available in two forms, powder and liquid. Organic pigments will break down in UV light, making the colors fade over time. Synthetic oxides (metal rust) will fade less, and all of the pigment we use at CHENG is synthetic. Dry pigments are more economical, but care needs to be taken when using them, especially because the colors can contain elements that are harmful when inhaled. Liquid pigments are dissolved in water, so they’re easier to work with, but the added water makes them heavier and can add to the shipping cost.

Here is a list of the some common colors and the metals that are used to produce them.

White – Titanium Dioxide

Red – Iron

Blue – Cobalt

Green – Chrome

Black – Iron

Using pigments is easy, you just mix everything together, but to get consistent results, you need to know a little bit of math. Color calculations are based off of the weight of the cement (the pigmentable material). A color loading greater than 10% will weaken the concrete.