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/Aquatic Gardens, Design, Construction & Maintenance

Foundation Coatings For Water Features

Thoroseal Use in Ponds


By Bob Fenner

Aquatic Gardens

Ponds, Streams, Waterfalls & Fountains:
Volume 1. Design & Construction
Volume 2. Maintenance, Stocking, Examples

V. 1 Print and eBook on Amazon
V. 2 Print and eBook on Amazon

by Robert (Bob) Fenner

Arghhhhhh! "Isn't there anything better (cheaper, faster curing, less toxic...) for coating and repairing concrete?" Oh yes, there are many great products and tool besides those commonly available (asphaltums, epoxies, rubberized paints), they're just not widely discussed in the hobby. I wish I were a mason for so many reasons; the Masonic Lodge and it's affiliates do so much good work around the world, and real masons are true craftspeople. Unfortunately, I learned about foundation coatings and repairs the hard way. By gooping up tools galore, tracking inappropriate materials hither and thither, and re-re-redoing work. You don't have to do the same though; you can learn from my mistakes and ignorance second hand.

Thoro is the name of my favorite brand of cementatious foundation coatings and repairs. Their formulations are very useful for coating, sealing and repairing concrete, mortar and other surfaces. They are fast to use and cure, relatively inexpensive, and they work! Don't lose faith if you can't locate Thoro's line as there are other manufacturer's with similar products.

Thoro System Products manufactures a wide range of coatings toppings, and sealants. This Section deals with in particular with Thoroseal Foundation coating and regular Thoroseal, both products are used to waterproof masonry above and below grade.

We used these products both as a color coat and as a primary waterproofing material, in addition they also are used for repairs. The two formulas differ for our purposes only in that Thoroseal is more expensive and can be dyed more easily to a desired color whereas Thoroseal Foundation coating is gray, and is suitable for use in situations where the desired hue is one of the darker shades: gray, brown, or black.

Tools and Materials:

Mixing vessel (5 gal.) Thoroseal

Drill (1/2" chuck) Acrylmix 60 (optional)

Paint Mixing/Bar Attachment Concrete Dye (optional)

Brushes Waterplug (optional)

Trowel Rags/Sponge

Putty knife Broom & Dustpan

Measuring cup Vacuum

Steps To Completion:

1) Prepare the surface to be covered. The surface should be clean and free from dirt, grease, and efflorescence, etc., making sure to fill all cracks and breaks in the surface. Use WATERPLUG or THORITE (or equivalent) for filling cracks and areas around pipes. Wet the surface.

2) Mix the Thoroseal per instructions on the bag. It is possible to mix Thoroseal either manually or with a power mixer. In practice it is laborious and time consuming to mix by hand, so if it is at all possible, USE a power mixer. A portable drill with a paint mixing attachment is the best solution. A 3/8" drill with a small paint mixer paddle attached is sufficient for batches of less than 1/2 gallon, but a 1/2" drill with a larger attachment is the most efficient.

3) In order to get a smooth even consistency, it is advisable to mix in batches of 1/2 bag or less. The recommended amount of water is 2 gallons per 50 lb. bag. If superior adhesion is required, the use of Acrylmix 60 is advised: 1 part Acrylmix 60 to 3 parts water. Add the water and any admixtures at this time. If any dyes are to be used, add them at this time and mix while gradually adding Thoroseal powder. Make sure to mix thoroughly; often the thickened mixture at the bottom of the mixing vessel will fool the person mixing the material into believing that the mixing attachment is at the bottom when in fact it's sliding over unmixed powder. For these reasons it's suggested that 2 five gallon buckets be used when mixing a bag.

4) The manufacturer recommends waiting for 30 minutes to allow the mixture to fatten. The mix will stay workable for up to 2 hours. It is possible to vary the amount of liquid in the mixture in order to apply the Thoroseal with a heavy brush or trowel. The initial consistency is like ketchup and "fattens" to one more like cake frosting.

5) It is important not to apply the Thoroseal too thickly or over dry surfaces. Should the Thoroseal dry too quickly it will crack. The cracks within the Thoroseal, if detected early enough, can be repaired by simply brushing the surface with water or a thin solution of Thoroseal.

6) The manufacturer recommends using 2 lbs per square yard initially and after 12 hours, a trowel coat of 25 lbs Silica sand to 50 lbs of Thoroseal for a 12 lb per square yard coating.

7) Allow a 48 hour drying period and fill the water feature.

8) Store the Thoroseal as you would cement, in a cool dry place.

9) Clean up of the powder can be accomplished with a broom or vacuum. The excess mixed material can be wiped off surfaces when wet using a wet rag or sponge, but when dry it must be chipped off or chemically dissolved using acid. For this reason it is important to be neat while applying and to clean as you go.

10) The coating should be lightly acid-washed per the Section of the same title, to reduce alkalinity, before introducing livestock.

In Summary:

What summary? That's it, for sealing new concrete, coloring, repairing over old, impaired surfaces, Thoro Systems and their products can't be beat for cost and effectiveness.


Aquatic Gardens

Ponds, Streams, Waterfalls & Fountains:
Volume 1. Design & Construction
Volume 2. Maintenance, Stocking, Examples

V. 1 Print and eBook on Amazon
V. 2 Print and eBook on Amazon

by Robert (Bob) Fenner
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