Final Curing and Aging
Hypertufa needs to fully cure to reach optimum strength. Portland cement strengthens as it dries, and strength is increased with slow drying. Fast drying results in reduced strength. Never leave hypertufa to cure in the hot sun or in a windy area. In hot weather, keep the object covered with plastic for a few days. Additional curing should be in a sheltered, shady area. Objects and containers should be allowed to cure for at least a week before use. Larger objects or thicker layers of hypertufa require additional time, up to 3 or 4 weeks.
Containers or objects reinforced with fiberglass may have exposed fibers protruding from the hypertufa (Fig. 13). After final curing, these fibers are easily removed by burning them off with a propane torch. Quickly pass the flame over the fibers and they will melt off. Do not concentrate the flame in any one area for too long because this will weaken the hypertufa. Of course, this should be done in a well-ventilated area and without contacting any combustibles.
|Figure 13. Stray fiberglass strands can be burned off with a propane torch.|
Portland cement has a high lime content that can damage plants if containers are used without aging. Aging occurs after final curing and is accomplished by leaving the structure exposed to the elements for 1-2 months. A better method is to construct the containers in the fall and leave outside for the winter. They will be ready for spring planting.
Many times the gardener will not have the luxury of allowing the containers to age over the winter. Faster aging can be accomplished by temporarily plugging the drainage holes and filling the container with a mixture of 3 parts water and 1 part vinegar. Allow the mixture to set in the container overnight. Unplug the drainage holes and rinse well, and the container is ready for use.
A natural and well-aged look is obtained by encouraging the growth of moss on the outside of the container. Hypertufa troughs look best in the landscape if they appear to have been in place for many years. Moss growth can be encouraged by painting the sides of the container with buttermilk and placing in a shady area. Within a few weeks moss will grow on the painted surfaces. This growth can be hastened by adding some collected moss to the buttermilk and pureeing them together in a blender before applying to the hypertufa surface.
Hypertufa containers are an easy to make garden project. When properly prepared, hypertufa can last for years with no maintenance. Hypertufa containers are relatively inexpensive and will add a creative touch to any garden.
Gardening with Hypertufa