A color chart tells you which color to aim at. A cured panel, made with the job’s own cement, sand, water and finish, is the only thing that tells you what you will actually get. Integral color cannot be corrected after placement, so the panel is the last point at which the answer is still cheap.
What the panel has to share with the work
A panel is only worth making if it is made the same way as the job. Every one of these changes the finished color, and every one of them is controlled on site rather than by the pigment:
- The same cement — same brand, same source. Gray cement mutes every color, most of all the bright ones.
- The same aggregate and sand, and the same supplementary cementitious materials. Fly ash and slag lighten the result and are part of the dose calculation.
- The same water and water-cement ratio. This is the largest single cause of batch-to-batch variation.
- The same dose, weighed rather than estimated.
- The same finishing method and timing.
- Cured the way the slab will be cured. Color follows the cure — where concrete dries evenly, it colors evenly.
- Exposed the way the work will be exposed, if the job is outdoors.
Making the panel
Mix the panel exactly as you will mix the job — the dose basis and the method differ between the two forms, and both are covered in full elsewhere rather than repeated here.
- Powder: blend it through the dry material before any water goes in, and give it the full blending time. See how to mix concrete pigment powder without streaks.
- Liquid paste: weigh it, charge it with the batch water, and rinse the container into the batch. See how to use liquid concrete pigment. Remember that Carbon Black 102 and Blue 201 run a lower dose ladder than the other five colors.
If you are between two dose steps, cast both. A second panel costs a few pounds of material and settles an argument that is otherwise settled by a whole pour. A pigment sampler is the cheap way to do this before committing, and the 2 lb paste pack is sized as a trial-batch quantity.
Judging it
Wait for full cure, and judge it dry. Wet concrete reads darker than cured concrete, so a panel judged damp is a panel judged at the wrong color. Then seal the panel the way the work will be sealed before anyone signs anything — sealers, cures and surface treatments generally darken the apparent color, and solvent-based sealers most of all. A panel approved unsealed and a slab delivered sealed are two different colors.
Look at it in the light the work will live in, and at the time of day that matters. A floor judged under site lighting and installed under daylight will not read the same.
Efflorescence is not the pigment
A whitish deposit can appear on new concrete as it cures, and it makes the apparent color pale or patchy wherever it sits. It arises from the concrete itself and is not a defect of the pigment, and it is more noticeable on colored concrete than on gray. If a panel comes up patchy and chalky, establish whether that is efflorescence before you change the dose.
What a panel cannot tell you
- How a different lot will read. A panel is made from one lot of pigment. Direct Colors publishes no lot-to-lot color tolerance for the liquid line, so where a job has to match across deliveries, order the whole job at once and hold it.
- What a prepared laboratory match will look like on site. Direct Colors will work up a match against submitted materials — send the cement and sand intended for the work. But a prepared match describes the color achieved in the lab, from those materials, under lab conditions. Approving it is not acceptance of a finished color.
- Anything about a mix you did not use. Change the supplier, the sack count or the fly ash percentage after the panel is approved and the panel no longer describes the job.
Common questions
Why can't I just pick a color from the chart?
Because a chart indicates a color; it does not predict one. Every sample Direct Colors publishes is cast on gray Portland cement and sealed, and your cement, sand, aggregate, water, finishing and curing all move the result. The chart narrows the choice. The cured panel is what you approve.
What does the panel have to have in common with the job?
Everything that touches the color: the same cement from the same source, the same aggregate and sand, the same water and water-cement ratio, the same dose, the same finishing method and timing, and cured the way the slab will be cured. If the work is outdoors, leave the panel outdoors.
When do I judge the color?
When the panel is fully cured and dry, and sealed the way the work will be sealed. Wet concrete reads darker than cured concrete, and sealers generally darken the apparent color, solvent-based sealers most of all. Judging a damp or unsealed panel is judging a color you will not get.
Direct Colors made me a sample. Is that the approval?
No. A prepared match describes the color achieved in the Direct Colors laboratory, from the materials submitted, under laboratory conditions. It does not predict the result on site, and approving it is not acceptance of a finished color. The cured panel in the project's own materials is still the only basis for that.
Do I need a panel for a small craft batch?
For a one-off piece, a sampler is usually enough. Make a panel whenever the cost of being wrong is more than the cost of the panel — any slab you cannot re-pour, anything where batches have to match each other, and anything a client is approving.
What’s Next
- Gray or white cement → White Cement vs Gray Cement: How the Base Changes Pigment Color
- Weight, not volume → Should Liquid Pigment Be Measured by Weight or Volume?
- Which black → Carbon Black 102 vs Charcoal 206
- Production batching → Weighing vs Pumping Liquid Pigment
- Paste and water → Does Liquid Pigment Change the Water-Cement Ratio?
- Chemistry by code → Concrete Pigment Chemistry Explained
- Specifying it → How to Specify Concrete Pigment Under ASTM C979
- A shade between two → How to Develop a Custom Shade
- When it goes wrong → Concrete Pigment Troubleshooting: Streaks, Speckles and Uneven Color
- Working out quantities → How Much Concrete Pigment Powder per Cement Sack or Bag?
- Working out quantities → How Much Liquid Concrete Pigment per Cement Sack or Cubic Yard?
- Mixing powder → How to Mix Concrete Pigment Powder Without Streaks
- Mixing liquid → How to Use Liquid Concrete Pigment
- Ready-mix quantities → How Much Pigment for a Concrete Truck Pour
- Every shade and its dose step → Concrete Pigment Color Chart
- The fundamentals → Integral Color Concrete
- Test first → Pigment Sampler · Pigment Calculator
Direct Colors. Shawnee, OK. Manufacturing the full decorative concrete system since 1997.
