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Tips |
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Q. What is the best mix of materials for ornamental concrete? |
A. The best mix is dependent on several factors regarding materials. Traveling around
the country it is noted that there are many differences in sand, aggregate (rock), and
even water. Therefore there is no such thing as one best mix that works for everyone.
We recommend starting with a basic mix measured by volume, not by weight. This mix
consists of three parts stone (washed pea stone), two parts sand, one part cement, and
one part water. What you are looking for is a pudding-like consistency. Try this mix and
adjust it until you have the mix that works best for you. Another mix which works well is
a mix of two parts sand, one part stone, one part cement. This
is the mix we use most of the time. There are many different
mixes. |
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Q. What type of release agent should I use? |
A. First of all you must use a release agent to make sure the concrete and the mold will
separate. The type of release agent used is dependent upon the material that the mold is
made of. Plastic molds, gel-coated fiberglass molds and steel molds work well using a
petroleum based release agent such as a non-detergent motor oil or used motor oil also
works. A vegetable oil based release agent is also suitable for these molds. Do not use
vegetable oil on aluminum molds as it will attack the paint making it sticky. Latex rubber
molds, on the other hand, should never be allowed to come in contact with any type of
petroleum product as it will soften or swell the latex making it unusable. For latex molds
we recommend a mixture of one part commercial grade Castor oil to eight parts
denatured alcohol (methanol alcohol). All release agents should be applied in a thin, even
coating on the interior of the mold prior to each use. |
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Q. How do I clean my molds when they have concrete or release agent build-up on them? |
A..
Keeping molds clean adds greatly to their life. Well cared for molds should
yield hundreds
of products before deteriorating. We recommend that you start the cleaning process using a
mixture of Dawn (preferred brand) dish soap and warm water. Clean your mold with the
mixture, using a soft bristle brush to clean detailed areas. Rinse thoroughly. If stronger
measures are needed, try a mixture of one part water to one part muratic acid and continue
using the brush. Rinse thoroughly. These methods are acceptable on all of the mold materials
mentioned. |
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Q. Is there any special way to pour concrete, and should I use
vibration? |
A. We suggest that concrete be poured directly into the center of the molds whenever
possible. This directs the flow downward and outward. Pouring slowly, this will aid in pushing
air out of the mold, thus allowing less air to be trapped by the concrete. Trapped air in
concrete causes what are known as "bug holes", which are unsightly flaws on the surface of
the concrete. The use of vibration will greatly enhance the appearance of your finished
product, as it will create a much smoother surface on your products. Vibration is important
for both flat and vertical pieces and can be achieved a variety of ways. Lightly bouncing a
filled mold, tapping all around the mold with a rubber mallet or clamp on vibration will help.
For the best and quickest results a vibration table is recommended for all molds but is rather
expensive. Vibration tables and clamp ons are not absolutely necessary.
We achieve nice finishes with out vibrating tables. |
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Q. How do I add color to my concrete? |
A. Adding color to concrete is done by adding concrete pigment to your mix.
Mix it into your water and then add the water to your mix. Your local
building supply or masonry store should carry pigments.
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Q. How do you antique concrete? |
A. There are two methods of achieving and antique look on concrete products. In either case
a base coat of paint is required, allowing it to dry thoroughly. We recommend Smith Paints at
717.233.8781 for a huge variety of high quality coatings for concrete. You may also use any
high quality latex exterior paint. The second step is accomplished in one of two ways. The
first is actual antiquing. This is done by applying a second coat of paint in contrasting color to
the base coat. This second coat should be thinned slightly and wiped off immediately with a
damp rag. This process will leave the contrasting color in all of the deeper detail on the piece
allowing the detail to show up much better. The second method by which may be applied
over the base coat is called dry brushing. This is done by using a dry paintbrush touching just
the tips of the bristles in your contrasting color. Brush off any excess paint on cardboard, and
then proceed to brush lightly over your base coated product. This will leave the contrasting
color only on the high points of the product again causing the detail to show dramatically. This
may be done with one or more contrasting colors and also produces and antiqued look. |
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Q. Should I seal my concrete? |
A. Sealer is optional on unpainted products. It does, however give the concrete and more
finished appearance. Painted products for exterior use should be sealed unless the paints you
use do not require sealer. This will give greater life to the paint and produce a richer
appearance in the finished piece. A clear concrete sealer is recommended. Do not seal the
bottom of any product as breathing space is needed. |
