Someone had mentioned to me using styrene beads as an additive to concrete to make it lightweight but not soak up water, freeze, and crack. (I am casting garden ornaments.) Do you know where I can find this? Home Depot doesn't have this.
Also, is there anything I can add to help get rid of surface voids? Even with alot of tapping, bubbles get trapped in my mold where they physically can't go up. Like around deep cuts. More gentle and gradual mixing seems to help, but there are still alot. There has to be a way to fix this.

And I forgot to mention "plasticizers". I would like to find these somewhere and in small quantities.

Laura As far as the styrene beads you can try to find a company that uses styrofoam. I have found that reground styrofoam from packaging works excellent. I purchase it from a local company that makes ornamental foam boards for EIFS installers and I buy the regrind. The virgin styrofoam called pearls are much too expensive as they cost $22.00 for 3 cu ft. (the regrind only costs $4.50 per 5 cu ft). I am trying to figure out how to regrind it myself as it would save me time and money. Anyone have any ideas? :rolleyes:

Try the link below for Butler Craft Supplies. Their superplasticizer is very easy & economical to mix & use. They're also really nice folks. Their website got zapped & is under construction, but most of their offerings are there. They are good about responding to questions emailed to them.
http://www.butlerscraftsupplies.com/

Don't know how quickly you're pouring after mixing, nor what formula mix you're using, but allow some time for the mix to release bubbles BEFORE pouring. Pour a little, tap a little, pour a little, tap a little. etc. Gives the bubbles a chance to escape from those troublesome niches. Use a high quality mold release like Crete-Lease or Goose Juice. Go easy on the mold release - more is NOT better! Wipe it on with a lint free rag instead of spraying (I saturate the cloth inside a zip-lok bag and reuse over & over), or spray, then wipe. Be sure your mold is CLEAN before pouring - don't give the air bubbles anything to cling to. Lastly, if your mix is a little too thick, it will trap more bubbles. This doesn't mean you should make it runny, but definitely not like brownie batter! If you are adding gravel aggregate, wet it, & allow it to drain before adding to the mix. Remember, anything you use to lighten the weight may compromise the strength of the concrete. I have used stratigically placed pieces of PVC pipe (even used a stainless steel mixing bowl once) to create hollow areas, which lightens the total weight - do this with care and consideration of the structure of the piece. If you put your mold on a piece of plywood, you can vibrate the board around the mold (a handsander with no sandpaper, a muscle massager, etc.) to help expel the bubbles. Again - too much vibration can cause other problems, but a couple of minutes two or three times during the first half-hour after pouring seems to do a good job without causing problems. Good Luck!

Thanks for some great information. I have been using a vibrator that my husband rigged that attaches to a drill and it seems to work well. I'm glad to know about the mold release. I also usually clean my molds well but the other day I was in a hurry so I "dusted" it out and I think now that may have been part of the problem. Where do you get those mold releases you mentioned? I'm glad to hear you've already used the PVC-I want to try it on a column. The only concern is our freezing weather but I think if it is kept with the hole down it shouldn't be a problem. Ever since I got the idea to do this everyone I know would say "ooo you know concrete is heavy". But I have been totally psyched about it and I think I'm hooked now. Besides, I found out working with the concrete isn't that laboring.

Yes - it's really addictive, isn't it?! I think it dates back to making mud pies as a little girl... Anyway - I sent you a private message with several info links. In your area, freezing IS a problem and, therefore, you might want to use an air entrainment additive, which is explained further & available from Butler's (web address on message responding to superplasticizers). Remember to test your "experiments" on stuff that won't break your heart if the experiment fails! Both mold releases I mentioned are available from Butler's. Do check out the sites I mailed to you privately; they contain links to more manufacturers and supply sources than you'll ever need!!! Most of the additives & supplies are available in small quantities online, which is often more convenient than trying to find them locally.
If you've been gently vibrating your molds, I would venture to say that your surface voids are caused by either the mix being too thick, pouring all at once instead of in stages, or the mold release problems I already mentioned. You didn't mention what formula you are using for your concrete/ For artwork, I'm a firm believer in mixing my own from the ground up. Because most mixes available at building supply stores are formulated for stuff like foundations, setting fence posts, etc., they do not have to be as unforgiving regarding surface blemishes, uneven coloration, etc. as the mix used by someone creating art objects. I'm sure you would like for the surface of your objects to be as smooth as a baby's bottom and the premixed stuff just won't do. Do check out the sources I mentioned - I think you'll find a lot of assistance for your particular concrete application, since the folks there are geared toward similar types of concrete work. Good luck!

Thanks again! Sounds like you've been doing this for awhile. I checked out those sites and they looked like they have great info but I haven't been able to spend a little time reading them. I have been using a premix and I think you're right. I am looking for a good recipe now I have limestone which is from this area but I sure wish I could get some granite dust. I will just keep looking for the granite. I'm glad to have talked to another "concrete chick" in the business. So I'm not the only one!

Ya'll make sure you hang around too, because a lot of us "hairy legged boys" don't know as much about the delicate nature of concrete as you do. That is the beauty of this material. You can make Christmas ornaments or the world's tallest structures out of it. That is why I use the signature I do.

Lord, no!!! From what I can tell, there are thousands of women out there cooking up small batches of their favorite recipes, making really cool looking stuff and trashing all kinds of kitchen utensils doing it

Thanks for the welcome, Ken. Concrete IS a fascinating substance with which to work. So facinating, in fact, that some of us womenfolks are becoming "hairy legged" because we no longer have time to shave our legs between pours!

I think having a sense of humor must be a requirement to enjoy concrete. That was hilarious about becoming hairy legged. I am glad my wife does nothing with concrete except listen to my whining!! Thank you all for giving us some real enjoyment. :p

[ July 27, 2002: Message edited by: ken ]

You guys are too funny. I would just like to add my legs only get hairy in the wintertime when I wear alot of pants. (That's a girls secret just like why we all go to the bathroom at the same time.)Just thought you should know. But anyway...I bought the limestone because I thought it would give a nicer color. I am trying to avoid that parking lot gray. What I REAlly am trying to achieve is something like that creamy white chocolate. Do you share recipes too? Or is that like asking for Aunt Mable's blue ribbon cheesecake recipe that she'll never part with?
Hmm.. I think I'd better get a signature now too...

Love the signature! Yes, I'll be glad to share, but just like Aunt Mable's cheesecake, a lot of making things come out like the original recipe is HOW it's made. I don't pretend to have a corner on the "great recipe" market. Mine is very similar to the ones posted on Cole Sonafrank's website and the one contained in the manuals from Silicon Folly. I'd strongly suggest that you download those as well as mine.

As for the grey color - the mix you are using is undoubtably based on grey portland cement. Portland cement comes in grey and white. For art purposes many people prefer the white because it can easily be tinted with a rainbow of pigments (again, available from Butler's) which are mixed in with the dry stuff before the liquid ingredients are added. I really have no preference one over the other. I find that with the formula I use, the castings come out a really light grey, which I personally don't find objectionable, but other folks seem to think it looks like caca! To each their own! Sometimes white portland can be a little hard to find, since it's primarily used for masonry & pool work. I would not expect to find it at the local home building chain store, but have heard that some folks DO find it there in their particular area of the country. It took me a couple of months to find it in my area, but that's because I was trying to avoid driving to the big city for a $10 bag of cement! Since I was new to the game (and still am), I was perfectly content to use grey portland for the time being. I still use it for some statuary work and when I want a more rustic look to a piece. It's only a little less expensive than the white, so cost isn't a real factor.

I'll get you the recipe, but it will be later on this evening (or the wee hours). Do remember that experimentation is a good thing - my doors are held open by, and the potholes in my driveway are filled with many experiments! Do try to read up on the process a little, because mixing concrete in small batches is an art in itself. Because of the small volume, chemical changes occur much faster, little mistakes become major malfunctions, etc. Expect some less than perfect results until you "get the hang" of it. Don't be discouraged if things don't always turn out perfectly at first - there is a learning curve with this. I have learned from trial and error (LOTS of errors) that sometimes it's better to think a project through and study the prior results before pouring again. Like I said before, don't experiment on a project that will break your heart if it doesn't turn out as planned. Patience is the key here.

Gotta run. Some of those leaves I have been eyeing are just the right size for imortalization by concrete and are "calling" me. Got to make hay while the sun shines! Talk to you later.

I got a chance to cruise those sites and I'm glad to have gotten them. When I would search before I would get alot of commercial stuff that did me no good. I will take your advice on practicing on small things. Baby's sleeping so I gotta get out there and try another....I may also experiment with some top staining or verdi gris maybe...
I saw the forum about the leaves also and it peaked my interest, let us know how it goes.
Hopefully sharing some of this info will eliminate some boo-boos maybe I can pass some experience on to someone in the future. I would like to check out your recipe though, thanks for the good feedback! Gotta go--happy casting!!

Haven't forgotten to email you my recipe - having to take some time out to make $$$. I just hate when real life interferes with my concrete life!! Keep checking - I'll send it soon. In the meantime, do print out those manuals from Silicon Folly & read them a few times. Although I personally don't do things exactly as it says there, it's a great starting point. Take care & I'll be writing you soon!

could someone please email those sites to me?

Hey Ken - RU out there? Can we move this "topic" from "Concrete Additives" to something more relevant, like "Stepping Stones & Statuary" or "Concrete Art"? The questions/answers are good, but not very "findable" especially since most of this forum serves folks in the Bigtime Concrete Industry. I learn a lot from those pros, but the amount of concrete folks like me use is minute, and the problems are different. I'm not even sure that this topic belongs in Decorative/Architechtural Concrete - seems like that refers to patios and concrete floors, which, again, are very different from the small-time artsy stuff some of us do. Hey I even read that someone out there is making concrete jewellry! Sure would like to see some of that!!! I picture itty bitty "This Mud's For You" trucks on a bracelet...LOL
By the way, I really enjoy this board. Despite the engineering stuff that is way over my dyscalculate head, I learn a lot here. Thanks.
Beth

Hi Tony - Sure. Didn't mean to be so rude. I'll post 'em for everybody and I hope that others "lurking" out there will post some new ones that I don't know about, too! The sites to which I referred in my post to Laura are dedicated to the stained glass stepping stone arts, which is not to imply that the information there is limited to those using glass in stones. Folks make all sorts of things from concrete. I do hope that if you have any questions, you'll bring them here, too, as this is a fresh environment for open discussion and everyone learns from everyone else, yaknowwhatImean.

First, I referred to a supplier who specializes in "stone" stuff. They are Butler Craft Supplies and their web address is: http://www.butlerscraftsupplies.com/
Their website is messed up, but they have most of their important items/prices posted. Email them if you need something you don't see or have questions. They're very good about responding and are nice, helpful folks.

The next links are other websites/boards dedicated to making art stones/objects. LOTS of good info, as well as ideas.

Silicon Folly is a website for stained glass artists and stonemakers. The link below takes you to the main page where you can find both forums (glass & stone) as well as lots of info (look at the "Manuals") and links to other relevant places. Their gallery shows nice stuff, but is not up to date. Many of the folks use Picturetrail albums to share their work. There is a "formula" for stepping stone concrete mix contained in "The Manuals" that many folks use. http://www.dmentd.com/folly/

Cole Sonafrank did a ton of research on the subject of making stepping stones and his site is a wealth of info about this art. He is a busy man and hasn't updated his site in a while, but the information and links are fabulous. His "formula" is the basis for many others who came after. http://www.elvesofester.com/mosaics.html

Steve Cole has a website and forum for stones, also. One can order a very handy spreadsheet from him that calculates quantities of ingredients for several "recipes" from the amount of mix needed. I found this to be an invaluable tool as I can't consistantly multiply & divide worth a flip. I trust spreadsheet calculations - I don't trust mine!!! You can also get to his forum (which, sadly, lost all its old messages a couple of weeks ago...) from the main page of his website. http://www.colebrothers.com/

Those were the main places I used when I started making this stuff (notice, I said "main" - it's a BIG web out there...). I used information from all of them, but I don't worship at any particular alter. I did a side-by-side comparison of as many formulas as I could find before coming up with my own mix. Same with techniques. I looked for commonalities among folks working in this medium, tried them, then made my own observations from my successes and failures. Still learning, still observing!

That should get you started, but don't be a stranger here! Come back and let us know what you find.
Good luck.

Hello Beth - Thank you, I create faux rocks and faux rock waterfalls. At times we make small waterfalls that can be transported, so we are always experimenting with addatives to make them stronger and lightweight. I hope these discussions will thrive in this area. In the past they always seem to dwindle away.

Hey Tony - Wow. Didja ever think you'd grow up to have THAT job description?!!! Sounds great to me! You might want to respond to Lise, who did a post right next to this one re: the stuff at Disneyland & how they did it. I'll bet you'd know more about it than I do. I started a new topic yesterday called Concrete Art for all of us. I figured it'd be easier to find for folks just "browsing through" than "Concrete Additives."
I (and I'm sure others) would love to hear more about what you do and some of your projects & methods.
Have a good one!

No additive discussion is complete without the universal improver for all things concrete. Polymer. It is great for how it handles, how it cures (it hold's water, bad for us, good for concrete). Once it's done holding water for cure it keeps water out. It increase flexural strength so you can cast or sculpt thinner and lighter. It protects concrete from acid rain and freeze/thaw cycles. Did i mention i think polymer modified concrete (PMC) kicks butt? Real PMC needs about 10% polymer by weight of cement. 10 lb of cement in your mix, you need a pound of polymer. That is 1 lb of actual polymer, not a pint of liquid (remember, a pints a pound the world around). So if your liquid polymer is 50% active you need two pounds of liquid to get 1 pound of actually polymer. Now, if you are good, you figure out how much water you use, and cut the polymer with water jussssssst the right amount so that when you use your diluted polymer as your only source of mix water you have perfect PMC. You have acrylic and SBR polymer. SBR has been the P in PMC bridge deck overlays for years. The right acrylic latex dispersion makes great concrete too.

It's late, i'm all typed out. Try polymer.

Polymer, huh? Now I take it that this stuff is not acrylic, and it's not melamine-type superplazticizer, correct? Can it be used with, or in place of acrylic or s'plazer? Where does one find this wonder substance? How is it supplied (liquid or dry)? Besides water reduction, what does it do for the mix? Is it compatible with pigments? What color is it, anyway?
Please illuminate after you've had your beauty sleep. Remember, I'm a little airheaded when it comes to most things technical, so direct your response down to the level of the compleat idiot, please! :p

I'll try to talk up from my level to the idiot level, though its a stretch for me! Powder v liquid, you can get it both ways. Liquids are usually cheaper, and sometimes better. Powders have to go through the extra process of being dried and that adds cost. Powders must be made of a polymer that can be re-disolved after they are dried, this is a extra problem liquids don't have. So liquids are best if you aren't trying to pre-bag polymer modified concrete(PMC) mix.

Types of liquid polymer. There are many and i'm no expert in them all, i just have experience with the couple we sell at work. We have good results with both. One type is SBR, a type of liquid latex (rubber) that improves durability but isn't the best on making concrete look water-repellent (though it is protected). SBR is used on concrete bridge deck resurfacing projects to make them bond well and resist salt and freeze thaw damage.

The other type we work with is acrylic latex dispersion (dispersion just means it's in water). Acrylic doesn't yellow at all, though i don't think the yellowing of SBR is noticable in concrete. It seems to make concrete more visibly water-repellent. I think the acrylic type is probably better for artsy stuff. All acrylics are not created equal, some spaz out when they are put in the high pH enviroment of plastic (wet) concrete. Ours, anyway, are made for concrete, whether they are SBR or acrylic.

They are both compatible with most all admixutres and colors, but test that idea before you make 10 yards of concrete like garbage. They do have some water reducer like activity, so you may want to reduce your super-p or MRWR, though the economics of taking out a little super-p are that big a deal in small batches. They can increase air entrainment, but again, if the DOT isn't looking over your shoulder it's not that big a deal.

About color, pigments for concrete are our primary business and latex/polymer is nearly universally good for pigmented concrete. No worries.

A tiny but of information about PMC. When you have PMC you are dealing with two cures. The first cure is our good old hydration, very important stuff. Concrete loves water, just enough of course, not to much, it hates too much. But polymer needs dry, has to dry, so there is a second cure with PMC, dry cure. Just keep it in mind, nice damp normal cure, then it has to dry out to "set" the polymer.

Just so you know, we sell this stuff in small quantites because we are little and we can. But our business is to sell big plants millions of pounds of coloring stuff for concrete.(don't i feel more important now) I just want to avoid the the shameless self-promoter label. Now, buy my polymer! Actually, if there are rules about it in the forum, I won't sell anything based on contacts here, i'll try to find the same stuff from someone else and send people there.

Found a new website last week that is packed with good info for folks doing art with concrete. http://www.makersgallery.com/concrete/handbook.html
There is a book for sale there as well as some very interesting concrete jewelry work. I'm not saying a word about the jewelry. Y'all check it out for yourselves!

Hi Beth! It hasn't been the season for concrete casting around here with our freezing temps, but I might just do a couple small projects in the basement. Depends on how messy it gets! I wanted to ask you...I know I read somewhere that you used an additive-a plasticizer or something- that made your surface very very smooth. I think it was you who wrote about that. Anyway, what was that product? I can't find the message now. Do you know?

Hey Laura - how y'all are?
The white melamine-based superplasticizer I use comes from http://www.butlerscraftsupplies.com/
It is used as a water-reducing agent as well as a conditioner to help increase the slump of the concrete and enhance hydration (How'd I do on the terminology, Big Time Concrete Folks? ) English translation: it makes the mix flo' mo' betta. When you use superplasticizer (follow mfg. diluting/mixing instructions - do not add dry to mix), start by adding only about 1/2 of the total liquid that your mix design calls for. Mix thoroughly after adding superplasticizer, as it takes 5-10 minutes for it to "kick in." THEN add more liquid in small amounts as needed. Much easier to add more liquid than to make the mix too sloppy. Better for concrete to be a little too thick than too runny.
Additive #2 would be the acrylic admix that I buy in the TILE asile (not concrete...) at Home Depot. Called "Acrylic Mortar Admix" mfg. by Custom Bldg. Products.
Additive #3 is the pozzolan material, Ultra Silicon Dioxide, which I get from the same place as the superplasticizer. It fills in the gaps between the larger sized particles in the mix and makes the stone more dense and smooth.
Additive #4 is nylon fibers (available from Butler's) for added reinforcement & strength.
Using a good quality mold release (Cressett's Crete-Lease or Goose Juice) SPARINGLY also helps the surface to be smooth. Remember that if your mold is not super clean and smooth, your concrete casting surface won't be either! Don't just blow off or wipe out those molds - get righteous with warm water & detergent. Dry thoroughly, then lubricate SPARINGLY. Store the mold upside down until you're ready to pour to keep dust and particles out. That's how you get surfaces that are smooth as a babby's behind.
Oh yeah - READ and FOLLOW the directions on the container of any additives you use. Different brands do not always have the same "dose" rates. If you have questions, ask! If you are following someone's mix design, use the exact products in the amounts that they specify or their formula may not give you the best results.
Sure do envy you that basement! With a basement, dare I say it, I could rule the world!! Unfortunately, down here, a basement would simply be an indoor swamp...
Have fun & happy holidays!