I often get asked by many hypertufa and concrete garden art enthusiasts where to find “silica fume” and “poly fibers”, also referred to as “fiber mesh”. Depending where you live, it may or may not be very easy to lay your hands on this stuff.

PLEASE NOTE! Silica fume is sometimes confused with fumed silica (also known as colloidal silica and pyrogenic silica). These materials have different derivations, technical characteristics, and applications. Silica fume is very fine like beach sand and completely black.

Silica fume and poly fibers are used as strengtheners, normally referred to as fortifying agents. They help make your cured hypertufa or concrete object stronger. Often, you’ll want to use one or the other for items such as stepping stones or very thin spheres. I do have some recipes sitting on my website that I’ll refer you to, in case you aren’t familiar with recipes and/or projects that utilize silica fume or poly fibers. Here are three of them:

Hypertufa Recipe Using Fiber Mesh (Poly fibers)  (refer to last recipe on the page)
Hypertufa Sculpture Recipe
Concrete Recipe For Very Thin-walled Spheres

How to Locate Silica Fume and/or Poly Fibers

My first suggestion is to call commercial concrete supply companies in your area. Many times they will have either fortifier, and will be willing to sell you a couple of pounds. (You don’t need much of either one in a recipe – unless I guess you’re making something collosal in size! ).

I’ve even read of people walking away with some for free, after explaining to the sales people what they will be doing with the silica fume or poly fibers. Seems the sales people get a kick hearing that Portland cement is going to be mixed with peat moss and water to make an odd concoction called hypertufa!

My next suggestion is to do what else … that’s right, find suppliers who sell via their online store. In doing a Google search today, I found EpoxyUSA.com carries poly fibers for a very reasonable price on the Fillers-Thickeners webpage. Note – I have no affiliation nor experience ordering from them. Perhaps you should contact them first to check shipping charges, etc. before you order. But I’ll wager a guess they are legitimate and probably fine to deal with.

Finding silica fume online seems to be more of a daunting task. I did find this link to the SilicaFume.org webpage. If nothing else, call them and see where you can purchase a small quantity online.

So, there you have it. I hope I’ve helped you locate two ingredients that do help make a difference in strengthening concrete and hypertufa recipes.

I received this email from Trisha asking me:

I have encountered a problem on my patio. After much research your website was the only one that made it clear there was a difference between concrete and cement.

We have a slab in our back yard (like a river rock slab), we wanted to skim it over with a smooth layer. We did so with what the hardware store told us to do it with, which was Portland cement. But it came out with lots of cracks and you can scratch your fingernail in it.

Is it because we used cement and not concrete?

My reply:

Hi Trisha:
First, thank you for telling me how you found my website. Glad my concrete-vs-cement page helped you.

Next … the easiest way to explain cement vs. concrete: cement is the dry, powdery product; once it is mixed with water and aggregate, it is called “concrete”. So no, your problem wasn’t in the terminology … your problem was a very ill-informed salesperson.

What a shame! You were given horribly wrong information!!! Even I know that you can’t put pure Portland cement onto a concrete (or rock) slab! And I’m no concrete expert by any means.

**First … I seriously suggest that you go back and confront the store manager about what happened because you’re not going to like my answer, meaning this isn’t going to be an easy “fix”, nor cheap. (Unless you clean off the crumbling Portland and forget about doing anything further.)

Let me tell you that the husband of a very close friend of mine was a professional concrete finisher and I picked his brain for you … and in a nutshell, here are some guidelines I can offer you:

1. Portland cement CANNOT be used all by itself in this situation! it needs some kind of aggregate added to it … so this was mistake #1;
2. You cannot just put a “skim coat” onto the slab … you need at the minimum a 2″ thick “layer” of concrete … so here was mistake #2;
3. The slab must be prepped with a “bonding agent” … this allows the new concrete to adhere to the slab … mistake #3;
4. There very well might be the need for the bonding agent to also be mixed into the new concrete;
5. The slab might possibly need to be wet down, before the bonding agent is applied;
6. You should use a 5-sack mix (called 5000 lb concrete);
7. The new concrete needs to be kept moist for 28-days – it will reach about 90% of it’s full cure (hardness) in that time frame – spray it down with your hose every day & night to dampen – this will help it to not crack and cure properly;
8. And then seal with a good quality concrete sealer after the 28 days.

And before any new concrete can be laid, you are going to have to THOROUGHLY clean/scrape off all the flaking Portland cement.

PLEASE NOTE: There could be other things to take into consideration before attempting this concrete project. I DO NOT know the particulars. There are many variables when it comes to concrete and the specific project.

***Bottom line … I suggest you call a reputable professional concrete company to add the smooth “layer” for you. Forms have to be built along the outside edges to hold in the concrete; expansion joints may need to be added into the wet concrete; depending on the size of the slab, interior wire “mesh” might need to be laid to help it not crack; the top must be finished off correctly to make it smooth, etc.

Does this overview of things-to-do help you? I hate to hear of problems like this. If nothing else, you deserve all your money back for whatever supplies and such that you bought for this project!

~~~

Trisha wrote back:

Thank you very much Claudia. Your info is extremely helpful!

We must be on the right track because yesterday we bought that same 5000 concrete mix and blended it with the Portland cement. It made a smooth finish like we wanted. It does not have the best appearance but it bonded and it is concrete. HA!

It is just a small 16 x 20 fenced in back patio, so anything done to the slab is better than what it looked like before.

Again thank you for all your info.

I received an email from Sue, who wanted to share with me this rather interesting bit of info:

You are my hero! I’ve been after the instructions on duplicating Little & Lewis spheres for a year!

I did some on my own and they exploded on my driveway (cold ball from house, 90 degree day= mess.) I just had to tell you about this recent disaster – maybe others can learn from this.

Sue

My reply:

Hi Sue:
Well, gee  Thank you for the compliment. That was very kind of you to take the time to say thanks!

Ummm … the only thing I am confused about is that you say you’ve been “after instructions” for a year to make hollow concrete spheres?? Did you search on the internet?? Because my hollow sphere articles have been available much longer than that. Maybe you mean you were thinking about it, because you just sent me into a panic that my Google rankings had dropped. But no, they are still at the very top! My rankings are:

how to make hollow concrete spheres — #1 and #2
how to make hollow concrete spheres — #1 and #2
how to make hypertufa hollow spheres — #1 and #2
concrete hollow spheres — #1 and #2
concrete spheres — #1
hypertufa spheres — #1 and #2

So you see, my instructional hollow sphere how-to pages are sitting up there at #1, waiting to be easily found.

Anyway … please know my information and how-tos should point you in the proper direction. And I am glad you found my site.

Wow, exploding concrete spheres!!  Now that’s a new one on me! If you had the video of the actual explosion, I’d be begging you to let me put it on my website so we could all learn from it, and maybe get a laugh, too?? (I’m not laughing at your mishap … just the mental vision of the sphere blowing up! ha ha)

But this incident goes to prove that temperatures CAN have a huge influence on the outcome of projects that use inflatable forms and Portland cement – both in the curing and otherwise, as your explosion proved! And this also proves that when making a hollow sphere the temperature of the air INSIDE the inflatable ball needs to be the same as the temperature in the area where you’ll be curing it.

Thanks again for sharing your concrete hollow sphere escapade!

I received an email from Jan R. asking me:

Hi there, I want to make a hypertufa leaf or concrete leaf fountain. After the leaves are made how would I form the fountain and to what? Got any ideas? Thank you for your time.

Sincerely, Jan

My reply:

Hi Jan:
Thank you for contacting me about making a concrete or hypertufa leaf fountain, which is a fun project to do. The answer to your questions will be rather difficult ones to answer at this point, as you’ve not told me how the leaves are to catch and/or collect the water; how many levels you want; or what sort of base you want the fountain to set on, to name a few.

Make sure you read through the ins and outs of working with hypertufa and concrete for leaves. Here are a couple of articles on my website that will be of help: Leaf Casting with Hypertufa: Tips for Success, and Concrete Leaf Casting: Super Tips From the Pro’s.

There are many variables I’d have to know in order to walk you through this, but basically here is what I believe will help you think this project through:

• Most crafters make two or three leaves set in a tiered fashion, and at angles to each other, which allows the water to spill over the edge(s) and finally collect in the bottom leaf.
• Joining all the pieces can be accomplished by mixing up a fresh batch of your recipe with bonding agent included in it and some bonding agent also painted onto the areas of where everything will be joined for good measure. (You would have to wait until the leaves were cured enough to be handled before you start joining them.)
• You need to seal the concrete or hypertufa leaves with a water-proofing sealant.
• You need to know how to install a simple pump in order to get the water flowing back up to the top-most leaf; you also need to get a pump that has the right GPH rating to effectively keep the water flowing.
• Another consideration – WHERE are you going to hide the pump and cords? Inside the base, or …? I wouldn’t think you want the pump and connections visible.
• You will need a GFI electrical connection available to plug in the motor for the pump. **There’s no side-stepping this requirement – water + electricity do NOT mix!

To learn about GPH and GFI, read this article on my website. Skim about half-way down: Garden Spitters Installation: GPH & GFI Considerations.

This is as specific as I can be for you at this time as I’ve no clue as to what actual shape/form you want your fountain to have. Nor how large you foresee the thing to be. What kind of leaves do you plan on using? Huge gunneras or something medium sized?

But, I do hope these tips help get you to thinking and sketching your ideas out on paper. Though not the easiest project, it is quite doable. Obviously your creative skills will really come into play with a project like this!

Good luck. I really hope you are successful with this leaf fountain project … personally I think there’s nothing nicer than the sound of trickling water in my garden.

I received an email from “Stoner” asking me:

I have been using a regular pre bagged “sand mix” cement for my concrete leaves. Is there a benefit to using something that I mix together myself ? Thanks. Stoner

My reply:

Hi Stoner:

Well, not necessarily. I mean, if you are very successful with and happy with the results of using the premix … “if it ain’t broke, don’t fix it!”  But of course, mixing your own ‘tufa or concrete recipe(s) allows you to tweak it, so that the recipe accomplishes what you want it to “do”.

Such as – maybe you want a really thin, yet very strong leaf casting. In this case, you might want to use an even finer sand than what comes in your premix, etc.

And then of course, you might want to add reinforcing fibers or a bonding agent, but of course that could be added into your premix.

I guess the point is, “it all depends” upon your desired outcome.

And perhaps mixing up your own might be a cost savings … don’t know what you’re paying for premix versus non-premix.

Good luck with all your projects!

I received a question from a crafter who had read my post about using hypertufa to skim coat vertical walls. She has a metal shed that she’d like to use the technqiue on and wondered if it would work in her situation.

I told her I’d found and saved some information years ago about this very issue and would post it. So … here it is. Anyone who works with a hypertufa or concrete recipe and uses a metal mold, or has something else made from metal that will be embedded into the ‘tufa or ‘crete needs to be aware of this information.

Aluminum
Embedded aluminum roof flashing, aluminum water stops, aluminum electrical conduit, introduced aluminum powder (sometimes used to foam concrete), or embedded structural aluminum shapes may all corrode in concrete or mortar. In all cases, a reaction that forms aluminum hydroxide and hydrogen gas occurs, and may cause expansion and cracking of the concrete or mortar. The common use of calcium chloride (or other alkali compounds), and dampness of the concrete increases the reaction rate. Usually, coating the aluminum with bituminous paint, impregnated paper or felt, plastic, or an alkali-resistant coating will prevent or sharply reduce the corrosion.

Copper
Copper embedded in concrete and/or mortar is usually roof flashing. Embedded copper is practically immune to reaction with corrosive alkalis, even if exposed to constant moisture. Copper will not react with dry, hardened concrete and/or mortar. Rainwater leaching, however, may bring chlorides in contact with the metal. Corrosion may occur and result in a green discoloration or runoff. Consequently, chloride admixtures should not be used in concrete if contact with copper is expected.

Lead
Lead will always corrode when in contact with fresh concrete and/or mortar. The high pH from calcium hydroxide is the cause of the corrosion. Cured, seasoned concrete or mortar will not react with lead. Corrosion of embedded lead flashing in mortar joints will usually result in the production of a lead oxide, a white discoloration. A special case of lead corrosion, called differential aeration, occurs when a lead strip is partially embedded in concrete so that part of the strip is exposed to air. The embedded section has a different electrical potential than the section exposed to air. The result is that the strip will become polar in the presence of moisture. Gradual corrosion and disintegration of the embedded lead will then follow. In such a case, and in all other cases, the embedded portion should be coated with epoxy, varnish, asphalt, or pitch.

Zinc
Zinc is highly reactive with alkalies and will deteriorate to some degree upon contact with fresh concrete and/or mortar. The reaction is limited due to a corrosive film that forms on the outer layer of the zinc. It protects the underlying metal from further reaction. Zinc will not react with dry, seasoned concrete and/or mortar. Embedded zinc will react with moisture and calcium hydroxide to produce calcium zincate. Zinc corrosion may also occur when galvanized iron, in the form of flat or corrugated sheets and rebar, comes in contact with fresh concrete and/or mortar. Galvanized iron is coated with zinc, and will react with moisture and chlorides in the concrete and/or mortar to produce zinc chloride. The result is expansion and cracking of the concrete and/or mortar. The metal should be protected with epoxy, varnish, asphalt, or pitch.

I received an email from Julie asking me:

Hi, my friend and I made our first hypertufa batches the other night, using a couple of your recipes, and want to make more.

My question: I want to put some glass stones and other things like nails on the outside of some pots and balls but am afraid they will fall out. If I put a binder in the mix will that keep the stones etc. attached?

Thanks for all your help! Julie

My reply:

Hi Julie:
Thank you for contacting me and I can answer your question – you don’t really have to add a binder into the recipe. Most crafters don’t. They just push/squish their chosen objects into the wet hypertufa or concrete.

Most embellishments – stones, marbles, mirror pieces, etc. – will stay “stuck”. But nothing is 100% fool-proof, so if some do end up falling out, use a little silicone caulk (or epoxy glue suitable for your project – i.e. glass and concrete) to stick them back. Just make sure you do give each item a good “push” into the wet ‘tufa or concrete.

That’s all there is to it. Good luck!!

~~~

And hey everyone … check out this idea for your next hypertufa or concrete project!

I found this great project the other day while I was surfing around online, and I would encourage you to read Kathy Cano-Murillo’s instructions for her concrete coasters project.

She explains how to glue pictures onto the back of clear glass pebbles before embedding them into wet concrete. How cool! And how easy!

This crafty idea CERTAINLY can be used to embellish larger garden art items, like hypertufa or concrete troughs, spheres … whatever! But I love her coaster idea. As a matter of fact … I always encourage new crafters to mix up small batches of ‘tufa or ‘crete recipes, in order to get the hang of working with the stuff – to make sure they are getting the ratios of ingredients right, how long it takes to cure, things like that.

Kathy’s project would certainly be a great one to try with hypertufa, too. You could make coasters, or perhaps small garden plaques. That way, if you are trying a small test batch because you’re new to working with hypertufa (or concrete) … if you had success then you’d have a nifty item to put in your garden, or something to give away as a gift.

Anyway … making sure your embellishments stay stuck really isn’t a major concern. So go ahead, and try adding something fun or whimsical to your next garden art project!

Gabby emailed me asking:

Hello, can you help me find the right type of paint for a large concrete planter? It is grey concrete and I want to achieve a tuscan look. Also where do I buy this paint?

Thank you sooooo much … Gabby

My reply:

Hi Gabby:
I will be happy to help and answer your questions.

#1) For information on what paints to use and info on what I think will be an easy way for you to get a tuscan look, please refer to my article: Decorative Sponge Painting.

Note: in this article I do not mention concrete planters (but I should – think I’ll add that to the page) but acrylic OR latex paints will be fine for your planter. Follow the directions in my article and you ought to have a nice long lasting decorative paint finish for many years.

Getting the “Tuscan look” you want will of course rest upon your artistic abilities. If need be … practice on a large piece of cardboard to get the color combination and appearance right. Sometimes my color choices aren’t always the greatest after I see them applied together. I have to do trial runs myself sometimes!

#2) In the USA, acrylic craft paints can be found at stores like Michael’s Crafts, Hobby Lobby, even the Wal-Mart in my area has a huge array in their craft section.

Or, regular latex paint can be purchased at stores like Sherwin Williams (though probably pricier than what you need to spend), Home Depot, even Wal-Mart sells latex paints, or most large hardware stores. You do not need to buy the most expensive paints.

#3) Make sure to apply at least 2 or 3 good coats of clear sealant, too. There are matte, semi-gloss and gloss finishes. For a Tuscan look I will say a matte finish is what you should use.

In addition, I suggest you take a few extra minutes to read all the pages I have in the decorative paint techniques section of my website. You’ll get lots more helpful how-tos that will not only help you have success with this decorative paint project, but any others you decide to to try.

Best of luck in dressing up your concrete planter! A Tuscan-type technique really isn’t a too-difficult decorative paint project for even a beginner to try.

I received an email from Hilda who asked:

I was delighted to find the information you provide on your website. I am making stepping stones from a silicon mold. They are basically 10″ x 10″ and 2″ thick. I need the “details/design” to appear of course.

I wonder which recipe would be best and ask what recipe would you recommend? I prefer a lighter color than the dark grey. Regular paint for added color, or stain?

Can’t wait to begin. I just hope the drying time is not too lengthy, as I need to make production on these.

Many Thanks, Hilda – Alabama

My reply:

Hi Hilda:

If you have details and designs that you really want to be a feature of your stones, then I’d opt for a pure concrete recipe, versus using hypertufa. ‘Tufa has peat moss in it, which doesn’t make for as smooth a consistency recipe. Plus, the hypertufa decomposes over time, and that will leave small pits and crevices in your stepping stones. So … use a concrete recipe instead.

For easiness, why not just go to Lowe’s or H-Depot and buy a big bag of ready mix concrete?? You certainly could use that and many crafters do.

Or, here’s a recipe on my website concrete art mold recipe that ought to be a good one for you to try.

**Please note: I have also seen this same recipe recommended on other sites, but the ratios are a bit different – 1 part Portland cement to 2 parts sand. I would say try a small batch of each recipe/ratio and see which one you like best. Remember … often times it’s trial and error until you get a recipe working just right for your particular needs.

You want a lighter color? Then you’ll have to find WHITE Portland cement, but understand it can be more difficult to locate. You probably won’t be able to find it at Lowe’s or H-Depot, but do some research (online, Yellow Pages, etc.) and call around to companies that supply materials to the stucco industry; or call swimming pool installation companies; or commercial concrete companies who might be able to steer you in the right direction. I’ve also read that ACE Hardware and the Ready Mix company sell it (if you have either of those in your area).

Also WHITE Portland cement will likely be about double the cost of regular grey Portland. Just so you know.

For those of you reading this who live in Canada, I have read that Target carries white Portland; also Pacific West Systems Supply Ltd; and Curtis Lumber. Again, call around first to see who stocks it in your area.

About stains vs. paints … either will work, just depends on your desired final outcome. Again I will refer you to my website to my stain and colorant guide. The link for the PDF guide is about 1/2-way down on that page.

About drying time … “curing” time depends upon a few factors, like the temperature and humidity to name two. But figure about 30-days minimum before you can feel safe to walk on them. But less time as far as being able to take them out of your mold (maybe a few days or so – but they need to keep curing after you remove them) so you can start a new one.

This “how to make your garden stepping stone project” information ought to get you pointed in the right direction so you will have success. Good luck!

Harold emailed me and asked:

What is the barrier or release oil that you recommend for hypertufa or concrete garden art projects? Thanks!

My reply:
Hello Harold:

If you refer to the following page on my website, approximately half way down the page you will see where I have listed a number of different release agents (or release oils) that can be used with success: hypertufa and concrete mold preparation tips.

There is also other good information on that page that just might be of use to you, too.

Hope this helps you. Good luck with all your garden art projects.