The-Artistic-Garden's Blog

Be Aware Of How Portland Cement Or Mortar
In Your Recipe Will React To Various Metals

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.

Hypertufa & Concrete Projects Tip
How to Make Embedded Items Stay Stuck!

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!

What Kind Of Paint Can I Use For A Tuscan Look
On My Grey Concrete Planter?

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.

Questions About A Concrete Stepping Stone Project

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!

A Garden Art Crafter Asks
“What Release Oil Do You Recommend?”

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.

Hypertufa Can Be Used To Repair Concrete
But There Are A Few Things To Keep In Mind

I received this email:

My 14-year old pond is showing signs of wear … the initial waterfall & trough were made of dyed concrete supplemented with mountain rocks. The concrete has some cracks and the mortar between the rocks is pulling away.

Can hypertufa be used to make repairs and rework my filter’s waterfall coming out of a larger filter so that it would appear similar to the original rock/mortar work? I’d like to purchase your Hypertufa How-To eBook, but I’d like to know if hypertufa is the correct medium to use or should I return to a portland/sand mix?

Also I’d like to supplement the large rocks with more faux rock. Thanks for your help.

My reply:
Hi:
These are some good questions and I’ll do my best to steer you in the right direction.

About hypertufa, the first thing I want to say is the whole purpose of using a hypertufa recipe is to replicate real Tufa rock. Peat moss is an all important ingredient in hypertufa recipes because over time, the peat moss decomposes and leaves pits and crevices like you find in real Tufa rock.

So … the use of hypertufa to make rocks will end up looking a bit different from the dyed concrete rocks and mountain rocks you currently have. I’m not saying this is a “bad thing” … just depends how similar you wish to match the job.

The other issue that comes to mind is the fact you said dyed concrete – can you replicate the color in whatever recipe you concoct to make new rocks and/or do the patch work?

But all this being said, sure you can certainly use hypertufa to spruce up everything. ‘Tufa can be colored with different colorants, and you can use white Portland cement if need be to better achieve a specific color. (However be aware it might be hard to find in your area.)

Here’s great info on concrete and hypertufa colorants sitting on my website: concrete and hypertufa colorant guides. Scroll down about half-way on the page to find the link to the PDF colorant guides.

I also have a hypertufa mortar recipe that goes beyond a plain portland & sand mix that you might find useful. Here’s the link: hypertufa mortar recipe.

Here’s a faux rock recipe that is great for projects like yours where constant contact with moisture is an issue: faux rock recipe.

And make sure to use a bonding agent on the “old” surfaces before you apply the new mixture, whether it be hypertufa or a concrete mixture.

That’s about it in a nutshell. This project more than likely will be a bit more complicated than just a simple “slap & patch” job.  

Oh … I do have more information in my Hypertufa How-To Manual about making forms for larger rocks and boulders.

Good luck with your project!

Concrete Statue Repair
How To Reattach A Broken Concrete Statue Head

I received an email asking for help:

I accidentely knocked the head off of a statue. Is there anything I can use to reattach it? It was my late Mother’s and I really need to fix it. Thank you for your answer. Irene

My reply:
Hi Irene:
Thank you for contacting me and I hope I can be of help. But first, you didn’t tell me what material the statue is made from. Because you found my web site and I deal with garden art, I will assume you are referring to a concrete statue.

Yes … you can fix it with an epoxy glue that is meant for concrete.  There should be a brand available at (hopefully) Lowe’s or Home Depot, as examples. Go to the paint department area and that’s where all the epoxy glues can be found. (Important for you to know, is that there really is no way to use a concrete mix to stick the head back on. Don’t even try it.)

Epoxy glue comes in 2 tubes that you mix together before you apply it to the concrete. Not a big deal to do, just a bit messy. Just FOLLOW the instructions –read them over first before you even open up one of the tubes.

Make SURE the concrete statue is bone dry!! Even a little bit of dampness in the concrete will very likely cause failure to your repair attempts.

The epoxy might be slightly visible when dry, but how “invisible” the repair will be is of course also dependent upon how neatly and carefully you can apply the glue.

I wish you the best of luck with this concrete statue repair.

When Should I Deflate The Ball When Making
A Hypertufa Or Concrete Hollow Garden Sphere?

I received an email from Charlotte who asked:

Did I miss something in understanding the concrete and hypertufa garden spheres instructions? Doesn’t the ball have to be deflated? If so – at what point? I’m so new at this that I would probably make a really stupid mistake about deflating the balloon too soon. Thanks for your help.

My reply:
Hi Charlotte:
Thanks for writing me. No, you didn’t miss anything … I guess I assumed that folks would know that you would have to deflate the ball after your ‘tufa or concrete garden sphere is cured hard enough – better to err on the side of a few extra days rather than deflating it while you still can detect moisture–meaning the mixture hasn’t cured enough yet.

Use your best judgment to gauge the right time to deflate it. Just make sure your sphere will be able to hold together.

Please read more about concrete garden sphere tips and garden sphere how-tos which will hold true for either hypertufa or concrete.

Sorry if this threw you for a loop. And please … no question is stupid  And I am glad you asked because now you are more knowledgeable about the issue of using the deflatable ball for your hollow garden sphere projects.

Good luck!