Calculating Pigment for Grout, Stucco, Mortar and Plaster

You’re listening to Direct Colors podcast Episode 19: Calculating Pigment for Coloring Grout, Stucco, Mortar and Plaster. If this is your first time listening, then thanks for joining us.  Many of our customers are interested in coloring grout, stucco, plaster and mortar but have a difficult time finding the right colors, especially blues, and small enough quantities. Direct Colors General Manager, Shawna Turner, is here to talk more about calculating for and mixing custom colors in these materials. Welcome Shawna.

Amie Nolen: Calculating pigment for so many different cement-based mixes sounds complicated. Is it?

Shawna Turner:  It definitely can be. The difficult part is the fact that very few manufacturers report the product contents on the side of the bag. Usually the technical data sheet will include the amount of cement in the mix but that’ s not always available so we often are forced to make an educated guess that many vary somewhat from product to product.

AN: Why is the amount of cement in the mix so important for getting the color right?

ST: Concrete pigment creates color by coating the cement particles with color so other ingredients are a less important part of the color equation. The pigment needed to achieve a specific color from our color charts is based on the amount of cement only rather than the total weight of the mix. Each mix is comprised of a 3:1 ratio of sand to cement and/or lime. If lime is also added to the mix, the cement and lime should be added together for the purposes of calculating pigment load. Whether you are mixing your own material or using a pre-bagged concrete ready mix, having this basic information can help you to determine how much pigment you need for a project. Because grout, stucco, plaster and mortar are cement, sand and possibly lime mixes containing no aggregate, colors can appear somewhat different in fact than they are on color charts. Testing is incredibly important when working with these materials and will help avoid mistakes.

AN:  There are several concrete calculators on the website. Which calculator should a customer use for these mixes as opposed to concrete?

ST: The calculator most useful for coloring grout, stucco, mortar and plaster is called the Custom Batch Calculator. The Custom Batch Calculator requires two pieces of information – the weight of cement and/or lime in your mix and the pound rating for the color chosen from our concrete pigment color chart. We recommend calculating both for batch size as well as the overall project. For example, if you planned to use one 80lb. bag of stucco mix and wanted to integrally color the stucco to Cornflower. You’d enter 20 lbs. for the cement/lime content and a “1” for the pound rating to calculate the amount of pigment needed for the project which is just under a quarter of a pound (.21 lbs.) per bag.

If you’re calculating for a sample, the pound output from the calculator is likely to be unhelpful so we’ve provided a link to other calculation options at the bottom of the page. For example, say you have about 5 lbs. of cement/lime in your mix and the amount of pigment needed for the chosen color, Royal Blue, is 0.1595 lbs. 0.1595 lbs. is a difficult number to work with so converting lbs. to teaspoons for such a small batch is very useful. Using a conversion website easily found with a search engine, we’ll need 15 teaspoons to achieve Royal Blue in 5 lbs. of white Portland mix. Calculating from lbs. to grams is also a good option. Gram scales provide more exact measurements, especially when measuring small amounts, and can be used for any small or medium sized project.

We also have a step-by-step video describing how to use the concrete pigment calculators that our customers have found very helpful in determining how much pigment to order for an upcoming project.

AN:  What about sealing? Is it necessary in all instances?

ST:  Outdoor stucco applications should be sealed with an acrylic or penetrating densifier sealer to protect the color integrity from the elements. Some customers prefer a light shine and the easy application our Sprayable Satin Finish Sealer offers, especially for stucco projects. Our  DCI Penetrating Lithium Sealer Hardener has a matte finish is perfect for grout projects where gloss isn’t all that desirable. This sealer enhances overall concrete durability and is a one-time application which is super. Sealing for interior projects isn’t necessary but acrylic sealers will deepen color appearance and add some gloss.

AN:  Thanks for making pigment calculations for grout, stucco, mortar and plaster mixes easier to understand. If you have questions, call one of our expert technicians at 877-255-2656 and we’ll help you select the best products and technique for your needs.  If you prefer email, send in a free online design consultation and we’ll get back to you within 24-48 hours.

Direct Colors DIY Home Improvement podcasts are produced twice monthly for your enjoyment and show notes can be found at directcolors.com/listen.  Feel free to add the podcast to your favorite RSS feed.  You can also follow us on Twitter, Facebook, Google+ , YouTube and Instagram. Thanks again for joining us!