Color Matching and Fill

April 4, 2003

Probably the area where crack filling owes more to art than to basic chemistry is when it comes to color matching.
In a perfect work, every stone would be dark, every crack would be hairline and every fill product would be clear. In reality, however, that doesn’t always happen.
According to John Maher, business development manager for Axson-North America, even the transparent products often have a slight amber tint to them, which may darken slightly over time if no pigments are added to them.
Where the decision is made to add some pigment, “It’s always a challenge,” he says. “The guys who have been in the business awhile know they can match many vein patterns. Fortunately, a lot of this is done on granite, which is a little easier to match than the marbles.”
His tip for color matching is to run a small amount of material and do a test, letting it cure in a cup before matching.
“You should match it dry because what matches wet will cure out dry and leave you with a different color or a different sheen,” he says. “Then, if you need to, go back to that base and color and apply it based on the original test or adjust it slightly. It’s not like you’re wasting a large amount of material, and it’s good to do the tests because once it goes on that piece of stone that’s about it.”
While Paul Klees of Bonstone says most installers develop a knack for color matching over time, he advises a person who may have worked with one material a great deal to take extra care if the job calls for a different type of fill material.
“You don’t want to take somebody who’s been using polyester for 30 years and then give them an epoxy and say, ‘Go out and do this,’” he says. “You have to practice because all products work differently.”
Klees adds that while the transparent products are nice in many instances, if you’re working with lighter and more porous stones you also have to be prepared to color match.
“Basically, when you’re working with granite and marble, you’re looking at using the same resins,” he says. “When you get into limestone and sandstone you want to use a different formulation because of the absorption. Those stones will absorb the chemicals so you want to have some fillers and stone dust to limit the absorption and some pigments to lighten it up. Otherwise, it will wet out the area around the patch and it will stay dark.”