Clay Craze

I received a call recently from a contractor who had applied American Clay three times on a project and it kept on cracking. It sounded a lot worse than it actually was. These areas were more smaller "crazes" than buckling "cracks", but still it needed to be resolved for a happy client.

Binders such as clay and lime once applied as a plaster lose all of their water to evaporation. If there is excessive water, the plaster is not compressed whilst drying small to medium cracking can occur called ‘crazing’ or ‘checking". Clay contains more water content than lime plasters. It also requires you to add water back to the surface while compressing it, so extra caution should be paid on this critical final step. Compressing ensures that the layers of applied clay have been pushed together to form a mechanical bond to the substrate. It's critical for a smooth and solid finish.

 In addition to the cracks, there was also greyish burn marks on the surface from using a steel trowel. The friction from using your trowel to compress the wall causes the plaster to turn grey from the steel material. Metal is heat conductive so a plastic trowel should be used especially on lighter surfaces. Both the burnish marks and the behavior of the cracks indicated it was a an issue in compressing the clay rather than a product or substrate failure.


Here's my prescription for bringing the beauty back!

• Scrape down any loose plaster and apply a sanded primer to the surface. This might be overkill, but creates a new vapor barrier and layer for the old and new plaster to adhere to.

• Use a plastic trowel to compress lighter colored surfaces to avoid unsightly grey burn marks.

• Compress clay when it goes to "set", "tack-free", or "leather-hard". This is when you can press your finger into it and no plaster is removed. You also know it's the right time to compress when the color starts to lighten. This requires less water to be used, which minimizes potential for cracks to form.



Clay - Ready for compressing!



 

 

 

Designing Texture!...Thoughts on Spec'cing

This is my treatise to wall treatments!! It's been 7 glorious years as an earth-plaster professional.

Hands, fingernails, and pant legs....caked and crazed with all sorts of pigments and aggregates. Wear and artifact from the layers of my steel hawk mirror...tall ceilings, narrow planks over stairwells, dead tired moments, and tales of great victories!

Over this time I have applied the earth. Clay, lime, marble, and sand have all spoken to me as the materials I respond to with creative intensity. My senses are delighted. I will admit my bias. I love things from the earth. AcryliCKS and plastic stencils have no place in my palette.

So when I receive a new client call, how do I determine the right earth plasters to use? Creative bias + knowing material properties is the formula for successfully specifying the "right finish for the right space."  It's important to know the differences between finishes whether you are a DIYer, interior designer, or architect. Before you pick up the trowel, consider these factors:

Damage will happen regardless of material.
Identify high-traffic areas and design accordingly. Wood, metal, or stone/ceramic tile have much higher impact resistance (psi) than common wall finishes so design a wainscott height (4'+) wall treatment and plaster above it. Also, if you are in the "space planning" stage, consider designing larger corridors or openings to allow for better traffic flow.

Repairability? Wearability?
Softer materials like clay are easier to apply and repair than lime-based materials. For an unsealed clay wall, you infill "ding" with product, let set then blend out with water. This is great news for the DIYers since you can easily and quickly fix your own walls. No toxic peel spray either! Clay is easy to apply and a great way to begin your creative journey.

But what about repairing clay with a large commercial space? It can be a "punchlist" nightmare. For heavier-use projects, go with a harder lime-based material. Lime has a higher psi (pounds per square inch) than clay. A stronger surface overall will not dent or ding as much as a softer one, so your maintainence costs will be less. Interestingly, lime plaster derives itself from limestone, so this plaster is essentially a stone veneer on your walls.

Functional Considerations
Paint is a coating. Plaster is dimensional. Earth plasters allow spaces to breathe, regulate humidity and even carry negative ions to neutralize electromagnetic charges from common office and household equipment. Paint carries a positive static charge so dirt gets readily collected on your walls. Earth plasters are bio-resonant so dirt and dander are actually repelled away from these surfaces.

Lime plasters are great for wet spaces to absorb and release moisture. Think Venice canals...viola! Venetian plaster was born. Then there is sumptious materials like Tadelakt, an ancient Moroccan plaster used in the centuries-old bathhouses. Go ahead, plaster your shower with this!

Eco-Faux
Personally, I think "faux painting" is outdated. Sponges, rags, and all sorts of other painting tools are used to decorate, gild, and ornate. Glazes, stencils, and murals all have their place but have a tendency to lend a more traditional Baroque look.

One reason "faux painting" turns me off is that alot of the products are acrylic and petroleum based and off-gas like your worst household cleaner! Give me a tannin stain, lime wash, or milk paint and it's a whole new beautiful world!

Earth plasters reflect the environment rather than copy it. Their chameleon-like textures can either reveal as ultra-contemporary or more casual and rustic. A nice contrast between ancient and modern. All take their roots in nature and that's what delights the senses the most!

Favorite Picks
I finished my first wall in 2001. As time goes by I continue to gravitate towards earth-based materials. Somehow the tubes and tubs of acrylics have become buried deep in the confines of my garage.

Here are my top picks for natural paints and plasters:

Your own hands...use your extra coffee or cabernet to make a tannin stain! Clearcoat with beeswax!
Stucco Italiano Lime Plasters: www.stuccoitalianoinc.com
American Clay Plasters: www.americanclay.com
Bioshield Natural Paints: www.bioshieldpaint.com
Real Milk Paint: www.realmilkpaint.com
Unearthed Purely Natural Paints: www.unearthedpaints.com


I enjoy sharing my experiences and knowledge with you! What a great journey this has been! These days my hands are still callused and stained and it's my continued mission to help educate and inspire the seasoned applicator or the one who just picked up the trowel and is feeling the new magic within. Thanks for reading! Trowel On!

Hey World!

I am proud to share my collection of creations with you! Since I began my plastering adventure years ago, I have had the opportunity to work with many different plasters and develop vast technique. Expiramenting is key. If you have more to offer, then why not offer more? Being surrounded by other like-minded artisans is crucial so I am glad you are here! I hope to share any tips or tricks I discover with ya in the days, months, and years to come! Cheers - Sherri