You can achieve various "looks" on the same stonework by using different styles of pointing. The most common three are, flush, recessed, and razed. To also add a different look, coloring can be changed to give even a wider assortment in the finish. One specific combination which goes well in our area is the use of the recessed pointing using white cement and yellow sand. This combination blends well with the light blue to green "IRON STONE". After all, they did make canon balls in the area during the Revolution . The stone is very, very hard.
Flush pointing: We pack the mortar completely filling the joints all around the stones. After the mortar has set and will not smear (1/2 to 1 hr. very depended on weather conditions) lightly brush the mortar with a wire brush. Use many light strokes vs one or two heavy ones. Directly after this step, go over the same area with a large soft brush to smoothen out the joints and remove loose mortar from the face of the stones. If at any time, any mortar smears, it is still a little to wet. Just let it set a little longer.
Recessed Pointing: Mainly the same procedure as above, it is just necessary to completely fill the joints when applying the mortar. In either case, it is not necessary to concern yourself with looks of the mortar when first applied. Just pack it tightly. The final appearance will come with the brushing. For the recessed point ing, just brush in the same manner until the joints are about 1/4" deep or so. The depth can be changed to match any existing work. A brush of 1" by 3" works good for me. You can cut down any wooden handled brush to this size if needed. Use short and repeated strokes to smoothen out the mortar. Then brush lightly with a soft brush.
Razed Pointing: The most difficult to learn for sure. Fill the joints completely , and about a 1/2" more in the center. How much over the face of the stone depends on your requirements. Within a few minutes of time, you use your pointing trowel to cut in the shape you want. With the point of your trowel touching the stones edge, and the body about mid-point of the joint, completely encircle that one stone cutting away the excess mortar. When you do the same thing to an adjacent stone, you should have a pointed ridge between the two stones. This takes a lot of practice , but once mastered, it goes rather quickly. You will not need to go over these joints with a wire brush, but the soft brush can be used lightly.
Matching Color: There are two types of cement, gray and white. Sand which is white, yellow or brown are the most common available . Using various combinations of these materials we can achieve a few different colors.
Outside of this color assortment, we need to add dye to get a wider range of color. Using different colors of sand with the gray cement gives vary little difference in color. It's using the white cement and a combination of brown and yellow which can give you a little control over the color. White cement and white sand does give you white mortar. White cement and yellow sand finishes up to a very light and pale yellow. Two combinations which we have had to use to match other work was two brown and one yellow with one part white cement, and one brown and two yellow with one part white cement. These combinations give a light brown, redish tint to the mortar. All of these items will vary with what is supplied on the local level. With the use of dyes, any color can be obtained. Here, you will have to check with your local masonry supplier to see what they handle. It may require many test samples to come up with the correct mixture for a certain match.
Mixing the materials completely dry will give a close indication of the finish color. Upon adding water to make your mortar allow it to dry for about 2 days to see the final result. When the mortar dries, it looks nothing close to what it did when it was wet. Dyes tend to be very concentrated , and a 1 pound or 2 pound bag was ment for a full bag of cement. If only one or two people are pointing, this is too much motar to mix at one time. So, you will need to keep control over your mixtures. Finish your test samples the same way you will be doing the final work. A brushed joint, or one which is made smooth with a trowel will have a different color using the same mixture.
TEXTURE: Mainly what has been stated above is to obtain a very smooth finish of the mortar joint. The sand mostly used is BAR sand. There is another type known a CONCRETE sand. The concrete sand is mainly used as it's name implies, for concrete. It contains very small stones which would show up in the pointing. At some point it may be needed to match existing work, but very rarely used. If the finish of the joint needs to be of a more course texture, a wooden stick may be used instead of a wire brush. A piece of burlap bag in combination with a wooden tool is also a possible form of finishing.