Obviously there are tricks to the trade, and concrete pro’s for a reason, but with a little practice you will find that pulling off a crisp, stamped impression of stone into concrete is not only doable, but extremely rewarding.
But be practical…start with a practice stepping stone on a piece of plywood, before you stamp out the front entry to your home. And like cooking a grand Thanksgiving dinner, make sure you have everything you need before you start the project.
Rubber gloves, a mixer, hose with nozzle, 5 gallon bucket to clean your trowels, working wheelbarrow, proper trowels, sponge, variety of stamps, releasing agent, a pump sprayer that works for the liquid releasing agent, enough cement and aggregate, integral color, marking paint to paint your stepping stones, and possibly a friend or two!
The recipe for concrete: 4 parts sand/aggregate blend + 1 part cement + water + one cup integral color.
We typically like to use a sand/aggregate blend mix. Make sure the sand is a clean mortar sand, and the aggregate mixed with the sand is smaller than 3/8”. Depending on what part of the country you live in, this may be pre-blended for you. Or you may have to order sand and aggregate, and mix them in your mixer as you are making batches. 3/8” aggregate is user friendly because it is big enough to give your concrete more strength, but small enough to be able to easily stamp.
Bags of cement can be bought at any hardware store. Make sure it is pure cement, and not a pre-mixed bag, if you are going to make your own mix.
Integral color comes in a variety of colors as your base color, and should be added to the water in your mixer before you add the sand/aggregate and cement.
You may do a small project with pre-mixed bags of concrete mix, but the cost per bag will add up quickly.
We like to compare the consistency of concrete for stepping stones to cooking…something like a very thick pancake batter. Not too runny, but also not to dry, and definitely well mixed! Remember, it is easier to add more water vs sand to your mix.
When looking at stones in nature, do all the textures look the same? NO! To avoid repetition, and to make your project look more natural, it is imperative to have at least 2-3 textures. Mix up textures from stone to stone, even use more than one texture on a single stone. You will find that the more random textures you have, the more natural.
Floppy stamps are a bit thinner, and are much more flexible. We use them primarily for stepping stones, water feature boulders, landscape edging, and for smaller pours of driveway stones. The concrete will be a bit softer when you use these stamps. You can also use Floppy stamps to stamp corners, columns, or contortions of boulders because of their increased flexibility. Rigid stamps are primarily used for larger flatwork jobs such as driveways, when you need to use a tamper into harder concrete, although you may also want a smaller floppy for corners and missed edges.
Form, or shape and size, is as important as texture! Meaning, if all your stepping stones are 18” and round, this form will overtake your awesome random textures. We tell everyone, texture is great, but great texture does not sell weak form. Spray out your stepping stones first with marking paint…force yourself to make more angular forms and varying sizes from stone to stone…then walk your painted stones…and make adjustments as needed…before you start mixing concrete!
Releasing agent is required so that the stamp will not pick up any concrete residue from the surface of the concrete. It will also allow for the most “crisp” impression onto the concrete. There are two kinds:
1) Liquid releasing agent: Applied with a garden sprayer onto the surface of the concrete and stamp immediately before stamping. Although it is a cleaner than the powdered releasing agent, your timing will have to be more precise…the surface of the stone will actually have to be a little drier, as the liquid will re-emulsify the surface of the concrete. No clean-up is required however.
2) Powdered releasing agent: Applied by a “rock skipping” throwing motion, this powder is a bit more user friendly. The powder actually creates a film onto the surface of the concrete, so the concrete can be a touch wetter, than if you were using a liquid releasing agent. The powder will also antique the surface of the concrete. Clean-up is more of an issue, as the powder will have to be hosed off the next day. Residue from the powder may get on the surrounding environment, including plants, buildings, and you.
There are three ways to color your stepping stones, and in fact all three may be used:
1) Integral color: A colored powder you put in the mix. Usually one to two cups per wheelbarrow sized mix. This will give a base color to your concrete.
2) Releasing agent: A powdered releasing agent which will leave some colored residue onto the surface of your concrete. This will antique your base color.
3) Stain: A stain is applied by sprayer onto the surface of the stones after they are cured. We recommend the RockMolds Stone Color Water based stain. It is non-toxic, and will remind you of painting with water colors on paper. Very user friendly. Multiple colors may be applied for a very realistic stone affect.
We recommend the “Thumb Test”. Basically, if you place your thumb firmly onto the surface of the concrete, and it is hard enough so you can’t break the surface, but soft enough to leave an impression of your thumb print, you are probably ready to stamp. If you begin to stamp and it seems too watery and the stamp impression is diluted, wait. Or if the surface is just too hard to take an impression, give a very light mist with the hose and another pass with the Mini Pool Trowel, and stamp it again.
We recommend RockMolds Stone Sealant sealant. It is a water based, natural finish, easily applied by a garden sprayer. This sealant will preserve the color in your stones, and may be applied every two years.
We recommend a mild soap such as “simple green” and a soft bristled brush. If the stamps are immediately hosed off after use for the job, without allowing any residual concrete to dry, very rarely will you have to clean them.
We recommend storing your stamps flat, not rolled up, out of the sun. This will keep your stamp’s “memory” flat, while protecting the polyurethane from UV rays.
Obviously with larger projects, such as driveways, you will be ordering a large amount of concrete in a truck. Speak with the company you are ordering from, explain your project to them, and they will advise you on a certain mix for that application. Is it for a driveway or a patio? Amount of SF? How thick? Will it be stamped? Will you have an integral color? Stealth fibers for strength?
A job this large will typically be done by a concrete contractor. Remember to check references, and look IN PERSON at some of their recent work. Remember, too good to be true, usually is. But, if you have the experience and the help for a large pour:
The equation to compute CY (cubic yards) for a concrete pad 4” thick: Total SF divided by 75. This will give a little extra on your order. If you have a 10’x10’ pad for example: 100 SF divided by 75, equals 1.33 CY. But, I would recommend ordering 1.5 CY to be safe. Plus a little extra concrete for a few stepping stones on the side? We call those bonus stones!
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FAQ – Frequently asked questions about concrete stone stamps