How do I stucco a wall and match existing stucco?

Old 05-09-00, 12:48 AM
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I am trying to stucco a few new walls to an addition. I need to know the eaxiest way to match the existing color to the new stucco. I already have the pigment, but am not sure how to mix it in with the product (pyrex?) that I already have. Any information woudl be helpful, as this will be the first stucco experience for me.
Old 05-09-00, 09:18 PM
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The easiest way is to have the color custom matched by a batch plant (not inexpensive though).

Since you're doing it yourself: the only way to match colors with any degree of success is to make small test batches (weighing and recording the weight of each ingredient [including water]) and allow them to cure. (I use a gram scale for such purposes). Full batches must be weighed also.

If volumetric measurements must be used, an old set of kitchen measuring cups and spoons is useful, but know that the color will be less consistent when it's transposed to a larger mix.

Sorry, but I am not familiar with "pyrex". Dry earth colors are mixed thoroughly with the dry ingredients (first with the cement, then they are combine with sand) before adding water. Liquid pigments are mixed with the water before adding to the dry ingredients.

Colored mixes should be mixed slightly longer than usual to ensure uniform color. When measuring or mixing use separate plastic cups or plates, and spoons for each mix.

The following may help:
Dry earth colors should not exceed 10% of the cement content by weight. If liquid pigments are used read the labeling for conversion / use, because they vary in strength from manufacture to manufacture.

Wear a dust mask and rubber gloves when handling dry earth colors. The dust is very fine; it's bad for the lungs, plus it's easily inhaled. On the skin it doesn't wash off.

If pyrex is a sacked mix product containing cement, assume that 15% of the sack weight is cement. Thus if the sack weight = 70 the cement content is 10.5 pounds.

1.5% to 2% dry earth colors by weight produces a pastel color. Between 6% and 7% makes a strong color. A quick way to gauge the range is by quarters 1.75%, 3%, 5.25% and 7%. Multipliers for the same percentages for direct conversion to ounces .28, .48, .84 1.12

Formula = percentage * .16 = multiplier (for ounces).
Multiplier * pounds in mix = quantity in ounces to add.

From prior experience I have found the typical range is between 3% and 5%. Once the range is isolated, it's reduced further by trial and error. (Generally the set product is twice as deep as wet mix). In order to age the new color add a very small amount of brown oxide or black oxide. Never use common "lampblack".

If using volumetric, do the following, but remember this is not a recommended process.
Use One Cup of mix for each test batch. Start with 1/16 of a tablespoon of dry earth color for each cup. Add up to 1 1/2 teaspoons per cup.

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