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This corner is for posting new information about the stone formulas and techniques. I'll post innovations, clarifications and modifications. All sorts of "ations"
or anything that's been tested and proved to work will be considered. The forum is the place for questions, this is the place for results. - Angel |
| 11/12/2001 - The Working Superplasticizer Solution |
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Melamine Superplasticizer powder must be dissolved before use. The essential step in doing this is to agitate
the liquid continually as the powder is very gradually sprinkled in. It's helpful to have some sort of
mechanical mixer like an old electric cake mixer, a blender or a small drill-attachment mixer. Use 1 ounce
of water for every tablespoonful of superplasticizer. This allows for the substitution of 1 ounce of solution
for each tablespoon of superplasticizer required in a formula. The solution will last for several weeks, but
I don't recommend that you make more than you plan to use in about a 2 week span. Calculate the amount you
will probably need. Example: to make a 14" stone you will need 4 tablespoons of "Superplasticizer",
which equals 4 ounces of the solution (4 oz water + 4 TBS superplasticizer). If you plan to make 4 stones
this size, you will need 16 ounces of solution (16 OZ water + 16 TBS superplasticizer).
Measure the amount of water into a plastic container. Start the agitation before adding the powder. Sprinkle
powder in very slowly while agitating constantly. Continue mixing after it is all added until the solution
clears and turns a slightly pinkish color. There should be no lumps if the procedure is followed
properly. If lumps are present, remove and discard them (these will NOT dissolve again in your concrete
mix). Use is easy if you keep the solution in a plastic pouring bottle or container. Keep tightly
covered during storage and at room temp. The superplasticizer will not re-solidify once it is well dissolved.
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| 09/21/2000 - Direct Mosaic Stones - By Denise |
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This is a method for direct mosaic stones that was posted on the WC glasschat forum by Denise (djd), I'm sure it will be a great help to us all. Thank you, Denise. "I have been making stones using the direct method for about 4 years, and they turn out great. I'm not an expert and I'm sure my way isn't the only way, but it works for me :) maybe this will help you too. Good luck and have fun!" DIRECT METHOD STONES Supplies: - Ready made stepping stone - Ceramic tile adhesive - Grout float or rubber scraper - Small notched trowel or comb - Sponge - Masking tape - Latex additive - Sanded grout - Sealer - Stained Glass Stones Purchase ready made stones from any home improvement or garden store. They usually have small rocks embedded in one side so you will be using the smooth side. Be choosy when picking your stones, sometimes they have chips broken off the top edges (they will work, but you will need to fill with more grout). Pre-Sealing I use a sealer on my stones and pots and other mosaics before and after attaching stained glass to them. I'm not entirely sure that the stones need to be sealed before, but terra cotta pots, wood and most other surfaces definitely need it. I just do because it's easy, cheap and gives me piece of mind. Pattern The pattern should be 1/4" to 3/8" smaller than the stone you will be using. When cutting out the pattern you will want to have at least 1/8" gaps between the glass pieces. If your pattern does not cover the entire stone and you will be using scraps to fill in the background, the grout will fill in easier if there are not wide gaps between the pieces (it can be done with up to 1" gaps but will take more than one application of grout). Adhesive After cutting all of your glass pieces there are 2 different ways of attaching stained glass to the stone:
Masking Tape Masking tape is used to make a form, so to speak, around the stone so that the grout doesn't spill off the edge and to make a cleaner looking edge. Just attach it to the edge about 1/4" down all the way around the stone. Grout I have used both un-sanded and sanded grout for my stones. I like the way sanded grout goes on better, even with larger spaces I rarely have to go back to apply a second coat, as I almost always do with unsanded. However, I think most people use the unsanded for fear of scratching the glass. I personally have not had a problem with scratches. In Minnesota, with the drastic changes in temperatures, I find that it is a good idea to use a Latex Additive instead of water to mix my grout. I have never had any glass crack in my stones and they stay outside all year. Follow the grout mixing directions that are on the package with the exception of using the latex additive rather than water. Mix to the consistency of peanut butter or toothpaste. Be very careful to not breathe in any grout dust, It's extremely bad for you. As far as how much to mix, I don't know, it all depends on the size of the stone, size of gaps, size of pieces etc. I usually end up mixing up too much but then I have some left over if I need to fix any areas. With the grout float or rubber scraper, spread a generous amount onto the stone working grout into the gaps and up to the masking tape on edges. Apply in a diagonal direction across the gaps to prevent the grout from being dragged out of gaps. Go over each area several times from all directions to make sure that the grout is fully packed in. Remove any excess grout from the surface by holding the float at a 90 degree angle to the surface and moving it diagonally across the gaps. After removing excess grout from the surface, allow the grout to firm up for about 10 minutes (½ hour if using water rather that additive). Remove masking tape from the edge of your stone. Wet a sponge in cool water and wring out all excess water. Wipe the surface of the glass & grout lines in a diagonal direction. This will remove remaining grout residue and smooth the grout lines. (Be careful not to rub too hard because you will remove the grout from the gaps and have to start over). Continue doing this making sure to rinse the sponge frequently until the glass is fairly clean. To smooth the edges, carefully wipe, following the edge of the stone with sponge. Wait about ½ hour and repeat the cleaning process. After the grout is dry you can polish with a dry rag to remove the haze left on the glass. Final Sealing I usually wait at least 3 days before I seal the stone. Make sure you seal all sides if you're using it outside. |
| 07/10/2000 - Pre-dissolved Calcium Chloride Solution |
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It's very convenient to make a Calcium Chloride solution in larger batches in advance. You won't need to wait while
it dissolves or cools. The only trick will be to control the concentration of your solution so you'll know
how much to use. That's very easy. For every cup of water, add 1 cup of dry CaCl. This yields a
100% solution in which 1 cup of the liquid equals 1 cup of the dry. If you need less, just add liquid to
match the dry cup measurement as stated in the formula. The batches can be made for several stones or saved
for later use. CaCl is an inorganic compound and is fairly stable in solution. I'd try to use it within
a few weeks, so it isn't wise to make it by the GALLON. Don't use a metal container for mixing. Mix
and store in plastic, tightly covered, at room temp. MIX well or shake just before use.
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| 07/10/2000 - Estimating The Volume Of Concrete For A Mold |
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To find a starting point for the volume of concrete needed for any size mold, fill it with water from a measuring cup (liquid or dry, the difference is not significant), counting the number of cups it takes to fill it to the very rim. That number will be the approximate volume (in cups) needed. 1/3 of that number will be in
cups of cement and 2/3 in sand. Taking into account that the acrylic liquid adds to the final volume and the dry ingredients will shrink a bit when moistened, you will at least have a good reference point. Maybe some people can calculate to the very last grain of sand, but when in doubt, over-estimate. Have a smaller stone mold or some other small plastic molds handy for use with any over-run that remains. You will NEVER end up with the exact amount. Don't worry about something so insignificant. Just be sure there's enough to fill a mold on the first pouring (and hope you won't need to pave the back yard with the baby blue mix that's left over). Adjustment gets easier with experience. I filled an 18" round mold with water and it came to exactly 28 cups. The formula I use has 9 cups cement and 20 cups sand (2 extra cups for the "pot") for a total of 29 cups. I usually have some over-run, but the next step down in volume just barely fills the mold. The total volume estimation can be also be done by filling the mold with sand, but that's HEAVY. Water works fine and you can just dump it out. The other ingredients don't add much to the volume of the mix. To estimate these, you can start with the basic measurements given by Cole on his formula page, or you can save some time and trust that the weeks of bumbling I did yielded some valid information. If you look at the 3 formulas in Part 2 of the Manual you will see a pattern to the increase or decrease of the smaller volume ingredients as the stone size changes. For example, there's about a ½ cup difference in Fumed Silica between the 14", 16" hex and 18" stones; 2 tbsp Superplasticizer; 2 tbsp Fiber; CaCl equals about 1/3 cup (up to the max of 1 cup in an 18" round). By using the tested formula for an 18" round mold we can easily calculate volume for the "Mega" molds. A 39" x 17" x 3" bench mold uses 50 cups of cement and 100 cups of sand …or a bit more than 5 times as much as the 18" mold. The new 18" x 4" birdbath mold will use approximately 3 times the formula for an 18" stone. For a birdbath, just multiply the ingredients for the 18" round by 3 (except for the CaCl which needs to be kept under 1½ cups). Use a 5 times factor for the bench. Tree rings and bricks can be done in the same way. Just find the established amounts for a stone closest to their volume and either use that or interpolate with a factor (plus or minus). This is probably a math nightmare, but hey, it's concrete, not rocket science. If you have access to a math teacher or engineer you could get them to calculate the mean cubic volume of a mold by size, then do the same with a 1 cup measuring implement and give you a factor to use. That's no fun. Anybody can do that, and you'd still need to know how to adjust the smaller volume ingredients. Frankly, a bench scares me to death. I'm in awe of the people who have done them successfully. I am NOT dragging one into the yard to fill it up with a water measurement. Thus, an interpolation from an established calculation is much easier and it helps to have verification from people who have tested the large formulations (thanks go to Jess and Chatty). |
| 06/18/2000 - Stone Materials Cost Calculation | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| This is a calculation of the cost of a 16" hexagon stone. It's based on a unit of weight or volume of each ingredient compared to the purchase price. I'm not going to list all the 6th grade math it took to come up with these figures, but rest assured that they were checked several
times by different people. If you want to see the complete calculations, e-mail me. INGREDIENT PURCHASE PRICE / UNIT | WEIGHT or VOLUME | COST / UNIT USED | Cement | $9.00 / 100 lbs | 1 cup = 8oz (1/2 lb) | 5 cents / cup | Sand | $4.00 / 100 lbs | 1 cup = 13 oz (0.8 lb) | 5 cents / cup | Sand (Pool Mix) | $12.00 / 100 lbs | 1 cup = 13 oz | 15 cents / cup | Calcium Chloride | $1.00 / 1 lb | 1 cup = 8 oz (1/2 lb) | 50 cents / cup | Superplasticizer | $105.00 / 20 lbs (shipped) | 1 tbsp = 1/4 oz | 09 cents / tbsp | Fumed Silica | $15.00 / 1 lb | 1 cup = 1/8 oz | 12 cents / cup | Fibers | $6.00 / 3 oz | 3 oz = 34 tbsp | 18 cents / tbsp | Acrylic Admix | $30.00 / 5 gal | 1 liquid cup = 8 oz | 75 cents / cup | 16" Hexagon Stone Calculated Prices : INGREDIENT | QUANTITY | COST / UNIT | TOTAL | Cement | 7 cups | 5 cents / cup | $0.35 | Sand [or Pool Mix] | 16 cups | 5 cents / cup [15 cents / cup] | $0.80 [$2.40] | Calcium Chloride | 1 cup | 50 cents / cup | $0.50 | Superplasticizer | 6 tbsp | 9 cents / tbsp | $0.54 | Fumed Silica | 1½ cups | 12 cents / cup | $0.18 | Fibers | 6 tbsp | 18 cents / tbsp | $1.08 | Acrylic Admix | 7 - 8 cups | 75 cents / cup | $6.00 | | | | $9.45 [$11.05] - TOTAL | It's strange that the ingredients which are so tough to get cost the least to use. I was almost unable to weigh the fumed silica. One cup on the scale didn't move it at all, it just sat there waiting for the "Mother Ship". You can get a cheaper mix by using ½ water with ½ Acrylic liquid or by using sand instead of pool mix (crushed marble). Fibers are based on a "pinch = 1 tbsp". Give or take a dollar for shipping expenses (the Superplasticizer calculation includes the shipping cost) and variations in prices. It's as close to an exact cost by weight and volume as I can get. Of course, it doesn't include the price of glass, but neither does the cost of studio pre-mixes. | ||||||||||||
| 06/18/2000 - Stone Lips |
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Lips If you fill stone molds completely by over-filling and screeding the surface, you're in danger of producing lips on the edges of the finished stone. Lips are those annoying little flanges of concrete that remain on the bottom of an unmolded stone. There are ways to prevent them and ways to get rid of them. I'll give you some advice from a great stone-guy who wrote in response to my question about these. METHOD 1 - Conc. Man's Solution "After you pour the piece and screed off the excess, take a thin plastic spatula and run it vertically around the edge about 1/2" deep into the piece. This action pushes the aggregate away from the edge and allows the cement cream to fill that space. After the initial set and surface appears dry, run the spatula flat around the perimeter, along the edge of the mold, pressing the concrete down from the screeded surface about 1/8" to 1/4" and by doing so, creating a slight bevel. Run it around several times to bring up the cream in the concrete, effectively filling the edge and compacting the surface. This may be all you need to do. Use the spatula or a trowel to flatten the ribbon of cream generated by the tooling of the edge. As the concrete gets firmer the tooling will be easier and look cleaner." METHOD 2 - Angel's Solution I've tried Conc. Man's technique. It's tricky. First time I did it I was left with a trough all around the edge of the stone…but no lips. Next time I just screed and wiped all the concrete off the mold edges. I used a spatula to push the concrete mix back toward the center of the mold, bringing up a little cream as it was moved. That worked and it's what I still use. I believe you have a right to both techniques and use the one that works. With experience we all seem to do something instinctive, because the lips problem disappears with time and a few people never see it. METHOD 3 - Under Filling I don't like under-filling molds. A thinner stone is a weaker stone, but this is another method used to prevent lips. I do notice in glass studios where they're done that none of the stones seem to be the same thickness. It's no doubt the result of under-pouring by the "seat of your pants". Removing Lips As for the existing pieces with lips, you can grind these smooth or even put a slight bevel on them. Use a coarse, hand-held grinding stone or lacking that, a coarse concrete or clay brick would do a decent job. Wait a day or two after they are poured so that you don't grind too much or chip out aggregate. |
| 06/18/2000 - Unmolding With Heat |
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The Heat Trick If, for any reason, you have trouble unmolding a stone because the mold was under-lubricated, or the gods forbid, you forgot to use a mold release, here's a trick to help. Invert the stone onto 2 dowels as usual. Wring out a couple of kitchen towels in HOT WATER and lay them across (and down the sides) of the mold bottom. Use your hands to work the edges of the mold until the stone drops free. Heat makes the plastic mold softer and more flexible. You can get the same effect by using a hair dryer to warm the mold. |
Send me mail at: angelica@siliconfolly.com
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