Monthly Archives: September 2013

How Much Grout Do I Need?

This is not a straightforward question because most of the grout does not end up in the gaps between the tiles. Instead, there will be some grout on the sides of the mixing bucket, on the mixing tools, on your gloves and last but certainly not least, on your worktable or floor. This last place is where most grout tends to end up, depending on the skill and experience level of the artist doing the grouting. However, with a little forethought and planning, even a novice can minimize the amount of grout wasted in this way.

Before I explain some practical ways to use grout efficiently, it’s worth the time to talk about what is theoretically possible if all the grout ended up in the gaps.

2 Pounds Per 10 Square Feet THEORETICAL

If you are doing large mosaic walls instead of smaller mosaic plaques, then you could THEORETICALLY gout 10 square feet of 3/4 inch glass mosaic with a 1/16 inch grout gap with under 2 pounds of grout, but again, how much grout you actually consume will depend more on your work methods than anything else. Also, the smaller the project, the more grout you will use per square foot because grout tends to be wasted at the edges.

Practical Numbers for Novice Artists

If I were to propose a rule of thumb for artists grouting small projects, I would say 1/2 pound to 1 pound per square foot, provided your grout gaps are 1/16 inch.

Here’s a better rule of thumb for novices:

A little wasted grout is better than a wasted mosaic.

The last thing you want to happen is run out of grout before you finish grouting the mosaic. You also don’t want the grout to start drying out before it can cure, and this is more likely when the grout is mixed up in small batches under a pound.

Sanitized For Your Protection: Plastics Are The Solution

Grouting requires that you smear grout to the edges of the mosaic and work it in so that inevitably a lot of grout falls off the sides of the mosaic and onto whatever you have beneath the mosaic. If the wet muddy grout falls onto a clean surface, it can be scooped up and reapplied to the surface of the mosaic. If it falls onto the floor or any other surface likely to have traces of dust, lint, hair or other contaminants, then it is best to discard what fell.

At our studio, we keep rolls of construction plastic and use this to cover our worktable before laying the mosaic on it for grouting. You can also use ordinary kitchen plastic wrap such as Saran Wrap to wrap your table. (Note that wrapping may be easier and more reliable than merely trying to tape or tack a layer on top of the table, which tends to get pulled up in all the activity of grouting.)

We also make sure that the worktable we use is large enough so that we have at least 6 inches of surface beyond each edge of the mosaic. This is important for making sure that we can scoop and reuse the clumps of wet grout that inevitably fall of the edge of the mosaic, but also for making sure that we don’t have to stop and clean up a mess on the floor before we step in it.

Misting Spray Bottles & Humidifiers

You should never add water to grout once it is mixed up, and you should not wipe the surface of a freshly grouted mosaic with a rag that is too damp because you can leach the pigment out of the grout.

However, it is important to keep the grout from drying out as it cures. For this reason, we often mist the air around our mosaics as we are grouting to make sure the air isn’t too dry if the heat or AC is running. We also run a humidifier if conditions are particularly dry. These same precautions can help extend the life of clumps of wet grout so that they can be reused.

If you ever pick up a wet-looking clump of grout and find that it has started to form a stiff crust on the outside, then it is best to discard it. Misting spray bottles and humidifiers will help prevent this from happening as quickly.

Putty Knives (And Serving Spoons) Used In Pairs

The main reason so much grout is wasted in the bucket is that it tends to get splattered and streaked up the sides of the bucket where it starts to dry out, and most people don’t notice it until it’s too late to do anything about it. The key is to be disciplined and remember to scrape down the sides of the bucket during mixing and immediately afterward, and after each time you scoop out some grout or do anything that smears it up the sides of the bucket. Try to keep your grout all together in the bottom of the bucket like a lump of dough.

A putty knife with rounded corners or an old serving spoon from the thrift store are good tools for scraping the grout into a lump, but you should always have a pair of these tools instead of a single tool so that you can use them to scrape grout off each other.

How To Mosaic a Patio Table

Replace Glass Top With Concrete Board

Glass-top metal patio tables can be used to make a mosaic table by replacing the glass top with 1/4 inch concrete backer board. The concrete backer board is roughly the same thickness as the glass top it is replacing, and it can rest on the rim of the metal table just as the glass top did. However, the thin concrete backer board can sag if unsupported, so marine plywood or pressure-treated plywood should be laminated to the underside of the backer board to stiffen it.

Note that the plywood should be slightly smaller in diameter than the concrete backer board so that it doesn’t interfere with the metal rim of of the table. Only the concrete backer board rests in the inside of the rim where the glass rested. If the plywood were to rest there, then the table top would be too thick and stick up above the rim instead of fitting inside it like the glass.

Steps For Replacing The Glass Top With Reinforced Concrete Mosaic Backer

  • buy 1/4″ concrete backer board from building material store.
  • measure glass top being replaced.
  • cut 1/4″ concrete backer board into a circle the same size using jig saw.
  • cut pressure-treated plywood into slightly smaller circle using jig saw with fresh blade.
  • glue plywood to concrete backer board using Weldbond or other PVA glue.
  • paint underside of plywood and its outer edge with multiple coats of outdoor paint.
  • insert table top into metal table base.

Repairing Edges of Concrete Backer Board

Concrete backer board sometimes has bubbles and voids that aren’t exposed until you cut across them and leave a weak spot or rough crumbly spot at the edge of the piece. You can also damage the edges of the concrete backer board during transport and handling. If this happens, you can repair and reinforce these weak crumbly places with the same thinset mortar that you use to attach the tiles.

Use Thinset Mortar Instead of Glue

Outdoor and wet mosaic should always be done with thinset mortar instead of glue. Thinset mortar is concrete with polymers added for strength and adhesive properties. You can also use the thinset for grouting the finished mosaic. An outdoor mosaic made with thinset will last many times longer than a mosaic made with glue, and that is why they use thinset for attaching tiles in swimming pools.

Using Thinset

We use Versabond brand thinset by Custom Building Products and add 1/4 pound of water per pound of thinset. Thinset comes in big bags that are inconvenient. We keep the bag of thinset in a 5-gallon plastic bucket with a lid. We slide the whole bag into the bucket and cut the top off the bag and scoop out what we need. Never try to pour it unless you like big clouds of dust that is dangerous to breath.

Finding The Right Table Is Easier Than Making The Wrong Table Work

I have always disliked the subject of mosaic tops for metal patio tables because I receive too many emails from lunatics who think the most important thing about the table to be mosaiced is that it is what they already happen to have on hand. It doesn’t matter to them if the table is broken or rusting to pieces or made of wood or already has an expanded metal mesh top welded in place.

For these people, it isn’t about finding a table that is appropriate for a mosaic top, it’s about making whatever they happen to have work, no matter how flawed or problematic or downright dangerous it might be. What’s worse is that when I take valuable time to email back explaining why the table is a poor candidate, they usually email back proposing some farcical method of making it work and wanting further comment.

These proposals show a lack of understanding of basic concepts, but what really makes them insufferable is that they are usually posed as questions asking me to explain why it would not work or why it wouldn’t make the process quicker or easier, usually in a pleading way. (As if my agreeing with them could somehow alter laws of physics or other aspects of objective reality… )

Reading their emails always brings to mind an expression used in the military, one that is blunt, crude and profoundly apt, like so many military expressions: You cannot polish a turd. How many times have I longed to type those words into an email reply!

Inspect Table For Strength And Stability

A mosaic table top can weigh significantly more than the glass top it is replacing. Before doing anything else, inspect the table to make sure it can hold the weight. Look for broken welds in particular, but also keep an eye out for the gauge of materials used for the table. Most metal patio tables are much heavier and stronger than they need to be, but factories make things lighter, cheaper and more disposable each year. If the table in question appears to be light-gauge and weaker than most wrought iron you have seen, then think twice before using it as the base for a mosaic table top.

Bistro Tables

If you use a small metal bistro table, then make sure that you don’t create a safety problem by putting a very heavy top on a table that is taller than it is wide. This can make the table unstable and easy to tip over. The heavy table top could easily injure someone if the table were knocked over by a casual bump. The solution is to anchor or weight the feet of the table, and a sock filled with sand and tied in a knot is often all that is required. Using wire to twist tie the table to the railing of a balcony is another quick solution.

Glass Mosaic Tile Is Best For Outdoors

Glass in nonporous and therefore impervious to moisture and freeze damage. Ceramic tile and stone are porous, and thus water can penetrate inside and freeze and crack the tile over time, sometimes very rapidly depending on where you live. Sure we have a lot of Roman stone mosaics from 2000 years ago, but those mosaics are in the dry warm Mediterranean basin and not west Michigan…

Remember To Seal Outdoor Mosaics

A few days after grouting, you should seal your mosaic with a tile and grout sealer. Tile and grout sealers are invisible pore sealers and not coatings that form a separate layer over the top of the mosaic. You wipe them on with a rag, and then wipe away the excess with a clean rag and allow to dry for ten minutes. Apply it 3 times or whatever the manufacturer instructions recommend.

How To Mosaic Bar Countertops

This article is about how to incorporate mosaic art into the design of your tiled bar top and is less about the basics of how you mount the plywood, cut a hole for the sink, etc. If you need that type of basic construction information, there is an article on HGTV’s website about how to tile a countertop.

However, I noticed that the HGTV article didn’t specify the thickness of the concrete backer board to use. For a floor, you must use 1/2 inch concrete backer board, but for a countertop, you can use 1/4 inch and probably should because it makes it easier to cut a whole for a sink with a jigsaw. You can’t cut plywood and concrete board at the same time because the blade gets dull too rapidly from the concrete, and then it rips the plywood instead of cutting it cleanly.  Make sure you have holes in your plywood before laminating.

Back to mosaic art and how to incorporate it into tiled countertops:

Recently a customer emailed me with some photos of a bar top she had mosaiced for her home, and I thought they were worth showing off for several reasons. Not only were the execution and color choices well done, but the design complemented the color scheme and decor of the room as a whole, yet still managed to have its own merits as mosaic art and not be mere tiling.


Mosaic countertops are easily replaced if the next home owner doesn’t care for the design. Unlike many forms of home renovation, these projects are relatively low-cost yet have maximum visibility and design impact. Photo courtesy of artist Charlotte Ward.

I think it is important to promote successful examples of architectural art because contemporary tastes have tended to converge on “basic black” and Bauhaus clean functionality in a monolithic way, especially when home remodeling is concerned. I certainly understand the reasons why: who wants to spend money to make their home less sellable? Who wants to customize their home in a way that most potential buyers might find unattractive?

Even if we have confidence in our own artistic and design skills, those of us who have lived in tight real estate markets have seen too many houses in “up and coming” neighborhoods where the previous owner may have had little money, but apparently had even less sense and spent $15 to $20,000 to add a room or porch that made no design sense at all or cut windows and doors where they made no sense or bricked them up with equal indifference. After being forced to consider such houses merely because they were the only thing on the market within budget, no rational person wants to even risk the possibility of spending money in a way that makes the largest investment of their life lose value.

And so we err on the side of caution and dismiss any individualistic ideas about home renovation and go for simple clean designs that lean toward the generic.

But that sort of thinking is why 9 billion houses have black granite countertops, and that is why those same black granite countertops will one day be the most despised, dated feature of those houses. If you doubt this, consider how many landfills full of real heart-of-pine paneling that you have seen ripped out of houses on HGTV home renovation shows. The wood paneling is rich-colored natural material (just as the granite countertops are rich-colored natural material). We just don’t like it anymore because it is so indicative of decades past because it was so widely used at the time.

The good news is that things like mosaic countertops and mosaic fireplace surrounds are easily replaced if the next owner or potential owner doesn’t care for the design. Unlike many forms of home renovation, these projects are relatively low-cost yet have maximum visibility and design impact. In short, mosaic countertops may be one of the few personalized home renovation projects you can pursue without jeopardizing the “curb appeal” of your house.


Brown copper and vegetable green are natural color compliments. This color combination also has connotations of old brass with a green patina, so there is an “antique” feel to the color scheme, which is very appropriate for a bar used for entertaining. Photo courtesy of artist Charlotte Ward.

Inserts In Regular Tiling

Note that you don’t have to mosaic the entire bar. The side edges can be regular bullnose ceramic tile, and mosaic art can be an insert in the middle of the regular tiling. All you would need to do is leave an un-tiled space in the middle of the bar (or instruct the building contractor to do so). Then you could put your own mosaic design in that space. Glass mosaic tile (typically ~1/8″ thick) is slightly thinner than ceramic tile (typically 1/4″ or 3/8″), and so you may need to build up the un-tiled space slightly with mortar before you mosaic it, but that isn’t difficult.

Photographing Mosaic Art -- Blue Mirror

How To Photograph Mosaic Art and Paintings

Not too long ago, I included a request in our email newsletter for customers to send us pictures of their mosaic art. I was pleasantly surprised by how incredibly good some of the mosaics were, but I was more than a little bit disappointed to see how poor some of the photographs were. To be brutally honest, some of the photos made me nothing less than angry. Here’s why:

If you are going to spend over 40 hours making anything, does it makes sense to photograph it without spending at least 4 minutes to make sure you have a neutral background and adequate lighting? After all, the vast majority of the people who see your art will actually only see the photograph of it and not the mosaic itself.

Note: You don’t have to be paranoid about sending me pictures of your art. The pictures I am talking about were so dark and/or blurry that I couldn’t tell what type tile was used in the mosaic. Seriously.

It was actually shocking that people could have enough patience and artistic sensitivity to produce the quality of mosaic they submitted to us, yet not display any of those traits when taking photographs of that same art. Many of the photographs looked like they were taken by a passing teenager who could care less: “I think I got a good shot. It’s a little blurry, and there’s shadows on the top corner, but you get the idea. Whatever. Hey, do you know what time Burger King closes?”

If this seems like a rant, it is, but my cheapo cell phone is capable of taking better photographs than a lot of what we received. And that is just the point of this long-winded introduction: YOU DO NOT NEED AN EXPENSIVE CAMERA TO TAKE PUBLISHABLE PHOTOGRAPHS OF MOSAIC ART AND PAINTINGS. You can take excellent photos with ordinary and low-end digital cameras provided you take just a little time (minutes) to ensure that you have adequate lighting and background.
Continue reading

How To Copy A Mosaic

An Easy First Project?

Many aspiring mosaics artists decide to copy an existing mosaic for their first project instead of making an original design on their own. Usually the person goes this route because they have no confidence in their ability to draw or their artistic abilities in general, or they believe that this decision will make the process of getting started easier. This is particularly ironic because making a tile-by-tile copy is in many ways more demanding of technical skill than making an original design, and it can also complicate the process of getting started, often in extreme ways.

This article explains some of the difficulties of exact copies and why you might want to use existing mosaics more as pictures to be copied and less as maps to where each individual tile should go. This article also explains the benefits of making a completely original mosaic design instead of a copy.

Why Copying Mosaics Can Be More Difficult Than An Original Design

Matching Each Tile?

Keep in mind that it is easier to cut up five or six pieces and pick the one that fits best than it is to trim a tile down to a specific size or shape. (The rejected pieces can go elsewhere in the mosaic.) If you decide to make a copy of a mosaic, you put yourself in the frustrating position of having to match each tile, which can be tedious.

The mosaic you are copying was made by someone who had practice cutting and arranging tile. Wouldn’t you want to get some practice cutting and placing tile before adding the extra burden of having to do it exactly like someone else?

Fundamentals First

Original designs allow you to spend more time playing with how you cut and arrange tile because you don’t have to be preoccupied with whether or not your results match an existing model. Also, if you allow yourself to make up your design as you go along (at least to a certain extent), you can decide to use a certain arrangement of tile simply because they fit together nicely or look a certain way.

Serendipitous Discoveries

It’s much easier to paint a beautiful picture when you allow yourself to keep individual brushstrokes that happened to turn out beautiful than it is to constantly be painting over them because they didn’t look like the model or what you originally had in mind.

If you decide to copy a work of art exactly, you have already constrained yourself to such an extent that everything you do is right or wrong. This may be a good technical exercise, but real art is about serendipitous discovery, and this is completely missing from the process of making copies.

Stress and Frustration

Some people decide to copy a famous Roman mosaic because successfully doing so would be some sort of unquestionable artistic accomplishment. This view is problematic, and not just because it implies that unquestioned displays of technical skill are what define great art. There is also the emphasis on results over process, and this can actually retard the development of technical skill.

It’s good to push and test yourself, but not every lesson is learned in this manner. Some of the more subtle lessons to be learned from art involve “listening” to your materials and processes. This does not happen as readily when our minds are in the same modes we use for driving through traffic or resolving problems at work.

When people make copies of art, they tend to judge their success or failure by how well their copy matches the original. This means their minds are more often in “work” mode than “art” mode, and they tend to overwork things or force things. At a minimum, this means that less was learned from producing the artwork than could have been. It also means that the process was more frustrating than it could have been and that the would-be artist is less likely to make another mosaic.

Matching Materials

Matching the materials used to make a particular mosaic can be extremely difficult, no matter if the mosaic is ancient or contemporary.

Many would-be mosaic artist squander their enthusiasm for making a mosaic by spending too long trying to find materials that match whatever they want to copy. Alternatively, if they ordered what materials that were readily available and created an original or semi-original design from them, then they could start work almost immediately when the impulse to create was still fresh.

This creative impulse is actually more critical than any particular tile or art material, so don’t waste it.

Problem Encountered When Matching Mosaic Tile

Molded Glass Tile

If the mosaic to be copied was made from molded glass tile, then the factory that made the tile could have been any number of countless factories that regularly start up and go out of business. Even the long-term producers periodically revise their product lines based on supply costs, process improvements and changes in demand. It is often impossible to match mosaic tile that is only a few years old simply because it isn’t manufactured any more.

Stone Tile

If the product is a stone tile, then there is not only the issue of how the manufacturer cut and finished the stone, but there is also question of what particular quarry it was sourced from. It’s hard to convince most Americans of the simple fact that not every basic material can be had as a commodity, but it is true.

Use SIMILAR Materials

Of course, the degree to which all of the above applies depends on how sane your are. If you are sane and practical, then you can make do with a similar material. If you need an exact match, you may want to consider therapy. Here are a few reasons why:

The mosaic that is being copied is usually a photograph of the mosaic and not an actual mosaic, and anyone who has ever photographed art (or glass in particular) can bear witness to the extent colors are distorted by photography and digital image reproduction, particularly blues and greens.

Also, consider your purposes in making the mosaic. Is it completely about the finished product looking a certain way, or is it also important that you learn about how art really works and have some fun in the process?

If it is all about the finished results, then keep in mind that master artists discover their art as much as they make it look like the original idea they had in mind. Not allowing yourself to vary from your original idea or picture is more likely to flaw your art than make it successful.

Ancient Mosaics

Ancient mosaics were exercises in using the limited color pallet available to render an image as naturally as possible. The lack of a broad color pallet forced the ancient artists to use draw objects in an outlined or stylized way, which make the art more interesting and more “modern” than an impressionistic rendering made from exact colors.

If the style and feel of the mosaic being copied ultimately derived from the ancient artist working with the limited materials he had available, does it make sense to try to artificially duplicate that same set of limitations or work with the limited set of materials you have available?

Sure, you may need to get a similar set of colors in a general sense (a white, a grey, a black, a terracotta red, a muted green, etc.), but when you push it beyond that point to needing exact color matches, you are in the realm of absurdity in my opinion.

How To Copy A Mosaic

Here are some principles for copying a work of mosaic art:

  • Copy the images in the mosaic, not each tile in the mosaic. Don’t use a mosaic as a “tile map” unless you are fine with the idea of spending most of your time matching the size and shape of each tile.
  • Consider making an interpretation of a mosaic design instead of an exact copy. This will allow you to develop and use your own rhythm for cutting and positioning tile instead of trying to imitate someone else’s mode of working.
  • Use similar materials and colors and understand that exact matching of materials is likely to be impossible for many mosaics, both contemporary and ancient.
  • Don’t copy a mosaic out of the mistaken belief that it would be easier or artistically superior to an original design.

How To Mount A Mosaic Tile Nipper For Easier Cutting

It is easy to mount a mosaic nipper to a scrap piece of plywood and extend the handle with a short piece of conduit or pipe. Extending the handle in this way provides mechanical advantage to the nipper so that much less downward force on the extended handle is required to cut a hard piece of stone or porcelain.

In this example, I mounted a Compound Nipper, which is the recommended hand tool for cutting hard mosaic materials, although a regular Tile Nipper could have been used. A mosaic glass cutter should be substituted for glass tile. A materials list for building this assembly is at the bottom of the page.

1.5-Inch U-bolts

Mounted Compound Nipper

Mounted Compound Nipper is secured to plywood board with 1.5-inch U-bolts. If your nipper has thinner handles, you may be able to use smaller U-bolts. If needed, everything from pencils to Popsicle sticks can be inserted parallel to the handle in the U-bolts if needed to help snug up the fit.

1-Inch Conduit or Pipe

conduit extends handle

Handle of Mounted Compound Nipper is extended with 1-inch conduit that is just slipped over the handle. I used an 18-inch piece of conduit. Conduit is better than pipe because it is lighter and cuts easier, but re-purpose whatever you have on hand. If the pipe or conduit you have is larger than 1 inch in diameter, you can wrap the handle of your nipper with electrical tape to bulk it up before pressing the conduit over it.



The U-bolts can be much shorter, but I used what I had in my workshop. The C-clamps secure the plywood to the shop table.

Scrap Plywood

scrap plywood

The piece of scrap plywood selected for the base should be roughly as long as the handle (18 inches) and strong enough to withstand the force of the cutting.

Use Caution Around Jaws

caution around jaws

CAUTION. The jaws of the nipper have sufficient strength to crush fingers or nearly anything else you are careless to get between them.Collection Pan

Collection Pan

collection pan

A box or tote is placed under the jaws of the mounted nipper as a “collection pan” to catch small shards, dust and usable pieces. It is best to raise the collection pan to just under the jaws, even higher than what we show in this photo.

List of Materials

You can mount your own mosaic tile nipper using these materials:

  • 1x mosaic nipper
  • 1x scrap plywood 1/2 inch or thicker, roughly 18 inches by roughly 6+ inches
  • 2x U-bolts 1.5 inches wide
  • 2x C-clamps (optional)
  • 1x conduit or pipe, roughly 18 inches long, inner diameter larger than handle
  • 1x roll of electrical tape (if you need to pad your handle to get pipe to be snug)
  • 1x cardboard box or plastic pan to collect usable materials and cutting waste

 Easier Cutting

It is easier to cut up 4 or 5 tiles and pick the piece that works best than it is to try to trim a piece down to size. The rejected pieces can be used elsewhere in the mosaic.

Sanded vs Non-sanded Grout

Sanded grout is recommended for grout gaps larger than 1/8 inch, but we recommend it for all grout gaps larger than a hairline simply because so many customers report problems when using non-sanded grout.

Problems With Non-sanded Grout

Some of the problems typically encountered with non-sanded grout include shrinking, cracking and crumbling. Customers often report a crack running down the center of the grout gap or the grout pulling away from one tile or the other. This may be partly due to the novice mixing in too much water or allowing the grout to dry out as it cured (such as can happen with excess heat/AC), but we noticed over the years that all reports of this nature were from customers using non-sanded grout.

Why Sand?

Sand is added to grout to give it tensile strength and toughness (impact resistance) just as gravel is added to concrete for the same reasons, so you should expect an unsanded product to be inherently weaker.

Will Sand Scratch My Tile?

Glass and Ceramic Tile

Sand will not scratch most glass or ceramic tile using normal installation methods. I’ve not ever experienced a problem with sand scratching glass or ceramic tile, and I suspect that cases where people report a problem are due to abuse conditions such as workmen walking across a tiled floor during or after grouting. Normal wiping with a damp sponge or rag should not provide  nearly enough force to scratch most glass and ceramic. However, if your tile has a particularly high gloss finish, then you may want to test it by rubbing a little dry grout or sand on a loose test tile before making your decision.

Sanded grout used on stained glass mosaic art

This mosaic is composed entirely of stained glass, which is notorious for being fragile. Even so, the sanded grout that was used did not scuff up the glass.

Polished Stone Tile and Marble Mosaic

Depending on the type of stone, polished marble tile can sometimes be significantly softer than the quartz sand used in grout, and it IS possible for sanded grout to scratch these materials.

Tumbled Stone Tile

Of course, stone with a natural or tumbled finish should not be capable of being scratched in any way that is noticeable, but here the issue is not scratching but staining. Unpolished stone is porous and can be stained by grout, and so you should always wipe the faces of the mounted tiles with a tile and grout sealer before grouting. Make sure you apply several coats according to instructions and thoroughly wipe away any excess and allow to fully dry before grouting.

Clarification About Epoxy Grouts

All of the grout advice on our websites refers to conventional grout (unless specified) and not the new epoxy-based grouts. The epoxy-based grouts may be recommended for the bathroom due to their enhanced water resistance and durability, but this can be accomplished by sealing a regular grout with a pore sealer. There is no reason to use epoxy grouts for most mosaic artwork, and there are reasons to avoid them. Epoxy grouts are significantly more expensive than conventional grouts, and I suspect clean up is not as simple as it is with conventional grout, which is messy enough as it is.


Clear Coatings For Mosaics?

Texture and three-dimensional elements make two-dimensional art much more interesting. Having thicker pieces and pieces that stick out make people want to reach out an touch your mosaic. Why would you want to cover that up with a material that scratches easily, can’t be repaired and turns yellow with age and sunlight?

Even if you do need to cover the mosaic somehow to provide a level surface, there are usually other means of doing so that don’t involve permanently coating the mosaic with these relatively short-lived materials.

My Mosaic Is A Table Top

Most mid-sized towns and cities have a glass shop where you can have a sheet of glass cut to a custom size and have the edges beveled (smoothed and rounded) with a torch. This same shop will also have small rubber pads for sitting under sheets of glass, and you may be able to use these for holding the sheet above your mosaic. If the surface of your mosaic is fairly rough and irregular in height, then you can use larger rubber stoppers and other means of holding the glass above the surface of the mosaic (such as a rim around the table).

I have seen some wonderful mosaic tabletops that were made from all sorts of found stones, shells and artifacts and then covered with a sheet of glass that rested on rubber stoppers. The overall look and feel of the table was like one of those curio coffee tables that have the glass tops over artifact collections, only the artifacts were closer to the glass cover, more visible and seemed to be part of the surface, which they were.

One important caveat: Make sure that the mosaic is evenly supported in multiple places and that no one piece of the mosaic can make contact with the glass if heavy objects are placed on the table. Otherwise you could possibly crack the glass.

My Mosaic Is A Floor

In general, I do not recommend making floor mosaics from materials with different thicknesses due to the potential for them to be a trip hazard and to be damaged by shoes and wheels and vacuums. If you do want to use material of variable thickness in a floor mosaic, make sure you do something that results in a level surface.

Consider Using Mortar Instead

One option is to press these pieces into a bed of thinset mortar similar to how crafters press tile into wet concrete to make garden stepping stones. However, be aware that mortar thins as it cures, so there is only so much height difference that can made up for by mortar when a tile is much thinner than the tile around it. In our studio, we solve this problem by mixing small pea gravel into the mortar underneath the particularly thin tile. We also have thin pieces of stone tile that we coat on both sides with thinset mortar and use as shims under thin pieces. Note that these methods aren’t really practical for large areas or commercial jobs.

Clear Epoxies For Floors

There are epoxy products that will last a long time by standards of flooring and architectural products, but I tend to think in terms of archival standards for fine art and making things as intrinsically durable as the Roman aqueducts. If you put a epoxy clear coat over the top of the mosaic, then you need to carefully review the manufacturer literature on the packaging and Internet. You want to look for information concerning scratch resistance and hardness and durability. You will also want to review the manufacturer’s recommendation for maximum recommended thickness.

Epoxy Not Polyurethane

If you do use a clear coat to make a level surface over a mosaic made from irregular pieces, then make sure you use an epoxy and not a polyurethane. Polyurethanes are not as hard and scratch-resistant as epoxies. They also do not bond securely to glass the way epoxies can.

How To Find Epoxy Clear Coats

These will not be in the tile aisle of the building material store. They are sometimes in the flooring department, but they are more often in the paint department. The important point is that they aren’t specific for mosaic or tiling, so don’t expect them to be sold for that purpose. Also, you should not expect professional installers to know how epoxy clear coats might be used to cover tiled surfaces, at least not in a thickness significant enough to compensate for differences in tile height.

Problems With Clear Coats For Mosaic

  • They cannot be removed or repaired by practical methods.
  • Installation is not very forgiving. You may have bubbles and haze that cannot be fixed.
  • They are not inexpensive and usually cost more than the mosaic tile.
  • They are not commonly used on mosaics, so professional installers don’t have experience with them as far as mosaics are concerned.
  • They scratch easily compared to porcelain, glass and most stone.
  • They turn yellow in ultraviolet sunlight, some much faster than others.
  • They won’t last the millennia that glass and stone mosaics are capable of lasting.

How To Remove Grout

The grout removal tool we sell is typically used to remove grout from between glazed ceramic bathroom tile, but it can also be used on mosaic art made from small pieces of glass. Dental picks and small screwdrivers may be more useful when the tesserae and grout gaps are smaller, such as typically seen in figurative mosaic art.

Here are some tips for removing grout using the grout removal tool and other scraping tools:

  1. Always do the work wet. Use a spray bottle to mist your work area and reapply as needed.
  2. Scratch the surface of the grout to break through any invisible pore sealers.
  3. Re-wet the grout by misting again. Allow the water to soak in. Wait at least 5 to 10 minutes and re-wet.
  4. Do not let any crumbled grout go down the drain if working in a shower or bath. Even in powdered form, it is still concrete and will accumulate and plug low spots in the plumbing.
  5. If you are working in a shower or bath, plug the drain and scoop out all the material with a spoon. We call them work spoons at my house. Make sure you explain to the spouse that they came from the thrift store and not the kitchen.

The Importance Of Small Uniform Grout Gaps In Mosaic Art

A common mistake made in first mosaics is a variation in the width in gaps between the tiles which results in the details of some areas being “lost” in concrete once the mosaic is grouted. The problem is a little sneaky because it isn’t visible until the mosaic is actually grouted, and so an artist can be experienced in other media and still get caught by this. In my opinion, it is one of the most subtle points in the mosaic learning curve.

Consider the detail in the photograph below:


Rose detail from artist Dorothy Stucki’s “To Begin and End with Nothing”

The artist wishes to depict the angularity and variability in the shapes of the rose petals, and has done good job in doing so. However, some of the gaps between the petals are almost as wide as the tiles. This means two things in terms of how the mosaic will look once grouted:

  1. The rose will not be as colorful because once the gaps are filled with concrete, about 50% of the surface area of the rose will be dull concrete at the same height as the red glass and just as visible. Gaps don’t look nearly as wide when unfilled. That is the crux of how the problem sneaks up on experienced artists.
  2. The rose will look conspicuously different from the tiling around it because it will be the only place where the surface area contains so much concrete.

The good news is that the problem is easily fixed. I have written an article about how to remove and replace glass mosaic tile to change a design before grouting.

Another relevant point is the importance of displaying and studying your mosaic before you grout it.