Casting Blocks

Place molds on a clean flat surface. You may want to protect the surface with plastic sheeting or absorbent papers.

Use a quick-setting cement, void of aggregate. My personal choice is a variety of anchoring cements listed in the article on Casting Materials. Anchoring (or hydraulic) cement is preferred for three reasons. First, mixed about 3:1 with water to a pancake batter consistency, the mix pours into the molds easily. It is thin enough that it does not trap air bubbles on the surface of the casting. The second reason for using anchoring cement is the speed with which it dries. Castings may be unmolded within an hour. The warmer the weather, the faster you can expect your castings to set. (Using cold water will slow the process somewhat.) And third is the water resistant quality of the cured casting.

OK! Mix a batch of blocks by pouring the water into your container first.
I use a 16-ounce plastic disposable cup. Gradually add three times as much cement as water, until you have a mix like loose pudding. Stir well and begin pouring into your molds. Because of the nature of the anchoring cement, you will not need to agitate the mix in the mold . . . But I do dab with a popsicle stick here and there along corners before moving to the next casting. Once you have used all your mix, rinse your implements. Using a putty knife or popsicle stick, skim the surface of the pouring along the flat back of the mold. Clean up your work area and prepare a place to put your green unmolded pieces.

About 40 minutes, later you should be ready to begin unmolding. The casting should be firm enough that you will be able to ease it carefully out of the mold.

Unmolding

Once the casting is firm, carefully loosen the sides of the casting from the rubber mold. Then pushing from underneath, work the casting from the mold. The casting will be green and fragile, so handle it with care. Leave out to dry completely for at least a day before you attempt to build with it.

(Note: Cement takes a full 28 days or more to completely cure, so refrain from subjecting recently-created structures to harsh elements of weather until they have fully cured.)

You will get to know areas of a casting that are more liable to break than others. If you do break a casting, handle the pieces with the same care you would a perfect piece. After the cement has cured, you will want to glue it together and use it.

Building Walls

There will always be shrinkage, or inconsistencies in your castings as they cure. And it must be expected that a small amount of filing or sanding will sometimes be necessary for linking units to fit snugly together. Do not force fit your blocks as they will snap.

Build on a scrap board a little larger than the base of the structure you plan to build. I protect it by covering it with plastic wrap, and place it on my lazy Susan. That way, I can turn the whole model without disrupting the freshly glued pieces.

To join pieces, use a waterproof adhesive, compatible with cement, plastic, and wood, as all three will usually be used in building your model . . .
	Be generous in the application of glue. Keep a check on squareness as you build – it is advisable to build completely around the model at each stage before continuing on upward. You will also want to check the sides of your structure for straightness.

To strengthen a model of larger size, pour cement inside the structure to a thickness of an inch or more, once the lower walling has been positioned and has set. Do not be concerned when the cement seeps into cracks behind your blocks. This seepage will help fuse and support the structure. If your plan is to have the structure lighted from within, place a short piece of 1" PVC pipe in the bottom of the structure before pouring the solid base to leave an open hole to work wires through.

Sealing Your Project

The last step in the building of any JigStones structure is probably the most important.

All JigStones structures need to be sealed as the final step. It doesn’t matter if you are building a little shack or a long bridge: If you don’t seal the structure you’re asking for problems down the road.

I’ve received three letters from JigStoners who have run into problems or have lost their structures completely because the sealing step had been left off. I know that it doesn’t always make sense, especially when the product of hydraulic cement is meant to seal holes in basement walls. But, it does need to be done.

What should you use? The final step is the application of two coats of clear, satin-finish, exterior, spray polyurethane. Some use Thompson’s Water Seal. Others use a material in the form of a painted coat of Dryloc Waterproofing.

After continued exposure to the outside elements, you’ll begin to notice that the weather is wearing away the detail of your building, or dissolving it completely. In some cases the stones curl or twist out of shape. Take the time to seal even precast pieces that you may buy.

You can’t overseal, and lightening bolts won’t come down if you’ve done a makeshift job or leave the step out completely. However, when you spend the hours it takes to create a handsome structure, you’ll want it to last.

Care of Molds

• Store molds flat, without any objects placed on them.

• Remove cement castings as soon as material has cured.

• Do not leave cured cement in molds.

• Do not be a fanatic about cleaning your molds – it is not necessary to clean them after each casting.

• You will not need a release agent while casting with your molds.