Epoxy Grout vs. Archival Quality Materials

Epoxy grout is preferred for pools because it is more resistant to pool chemicals and staining, but it shouldn’t be used on art object or plaques that might be around for decades or centuries as heirlooms.

Epoxy is a resin of long carbon compounds. Long carbon molecules are prone to breaking overtime because they contain stored chemical energy. They are vulnerable to things like oxygen radicals and UV radiation.

On the other hand, traditional grouts and mortars are made from kiln-fired sand and limestone and clay, which are all basic mineral substances with little stored chemical energy, all materials that last for geologic ages.

Traditional grouts and mortars age and fail more gracefully, and that is very important.

You can use acid to remove failing grout cleanly and efficiently, but what do you do with epoxy grout that has turned into cracked yellow plastic that is still sticking to the tiles?

When heirlooms are discarded, it is usually because some part of the material itself has failed in a way that cannot be removed and replaced easily from the materials that are still good. Use materials that age well.

Archival-Quality Materials

We use archival-quality materials for our mosaic artwork and recommend that you do the same.

Archival-quality materials are materials that have extremely long or unlimited lifespans under certain conditions. They are inert or decompose gradually instead of catastrophically. They don’t create acids or other chemicals that damage other components of the art.

Snuggle Bros Forever. Sweet Pea and Stinker take a break their normal nap schedule to squeeze in a quick two-hour snooze in the rocking chair.
Snuggle Bros Forever. Sweet Pea and Stinker take a break their normal nap schedule to squeeze in a quick two-hour snooze in the rocking chair.

What We Use


We use traditional portland-cement grouts such as Custom Building Products’ Polyblend Plus brand and Mapei’s Ultracolor Plus brand. You can get those at local building materials stores.


We use Weldbond on dry indoor mosaics.

White Polyvinyl Acetate (PVA) glues (such as the Weldbond we sell) are what museums and archivists use to preserve artifacts of wood, bone, paper, and other vulnerable materials. PVA has great properties all around: non-toxic, stable, inexpensive, non-yellowing, great adhesion to porous surfaces, and easy to handle.

Thinset Mortar

We use Versabond Thinset Mortar for outdoor and wet mosaics. Versabond is a portland-cement-based mortar with PVA added. It is strong as hell when fully cured.

I recommend buying the 25-lb bag from your local building-material store plus a 5-gallon bucket with lid to store the thinset and protect it from humidity. I have stored and used bags for years inside a 5-gallon bucket with lid and experienced no discernible loss in strength or bond-strength.

Mosaic tiles require fossil fuels and minerals to be made. Don’t use them for something disposable. Make an heirloom instead!




14 responses to “Epoxy Grout vs. Archival Quality Materials”

  1. Bonnie Lankford Avatar
    Bonnie Lankford

    How long do you keep grout once it is open if it is kept in a plastic container with a lid?

    1. Joe Moorman Avatar
      Joe Moorman

      Hi Bonnie,

      If you are talking about the new urethane/epoxy grouts that come as pastes, I think the package explains that they have to be used within a certain time of activating or opening. If you are talking traditional portland cement grouts, then those can keep for years (possibly decades) if perfectly sealed off from humidity.

  2. Sharon Tepe Avatar
    Sharon Tepe

    I really love this article. I have debated using epoxy grout for a while. I make a lot of outdoor objects, and many artist who do that have switched to epoxy grout. It just always seemed like more of a pain to do it, but I did like the idea of not having to seal my work. But after reading your article, I will just stick to regular grout. I currently use Mapei Keracolor grout and Lacticrete black, when I can find it. Thanks for such a timely article.

  3. Donna Conklin King Avatar

    Thank you Joe. That was very enlightening.

  4. Marilyn Figueroa Avatar
    Marilyn Figueroa

    As a preservationist of museum collections, I greatly appreciate this information. I am always looking for information on archival and durable materials for work-related collections. Now, I’m going to consider it for my mosaic hobby as well.

    Thanks a lot Joe.

  5. Sue Hague (Mrs.) Avatar
    Sue Hague (Mrs.)

    can you do an article on doing grout free mosaic projects? do’s and don’ts, please?

  6. Susan Altman Avatar

    Joe, thanks so much for pointing out that most mosaics require fossil fuels as an input. It’s way too easy to overlook this, since most mosaic artists never encounter this part of the production process.

  7. Sandy Staiger Avatar
    Sandy Staiger

    in reading about epoxy grout mostly used around pools and wet areas…….. would you suggest it being used on indoor shower tiles? I am re doing my shower………. commercial contractor will be setting ceramic or porcelain tile on 3 walls using an “epoxy” grout so they tell me. I had plans to take a portion of the 4th wall approx 2′ x 4′ and have them adhere and grout in my 7 pre finished fish pieces. Should i be concerned with this epoxy grout??

    1. Joe Moorman Avatar
      Joe Moorman

      Shower stalls aren’t portable objects of art that are likely to become a family heirloom. They are likely to need repairs or replacement after a few decades, and so the epoxy grout isn’t a concern.

  8. Laura Paull Avatar
    Laura Paull

    Love this blog post- so valuable. Thank you Joe!

  9. Sharon Tepe Avatar
    Sharon Tepe

    In regard to this article, do you ever use an admix with your thinset when doing outdoor applications? Do you think this compromises the integrity of the thinset over time? I never used it initially, but now use it a lot for my outdoor mosaics. I use Mapei thinset for glass with the Mapei additive. I was just curious about your thoughts on this.

    Thank you,
    Sharon Tepe

    1. Joe Moorman Avatar
      Joe Moorman

      Hi Sharon,
      The thinset already has a polymer in it. I wouldn’t add an admix without checking the thinset manufacturer recommendations of what could be added or testing it on my own. I don’t think there would be a problem of bond degradation over time. If there were problems, they would be in the initial hardening such as happens when two incompatible polymers interfere with each other’s polymerization or something along those lines.

      1. Sharon Tepe Avatar
        Sharon Tepe

        I use Mapei thinset and Mapei additive. The Mapei thinset already has polymers, but the additive has some as well. It is supposed to increase bond strength, flexural strength and freeze/thaw durability, according to their website. I just wondered if something like this would fail over time. I have never used the Versavond thinset. I suppose you can purchase this at tile companies.

        1. Joe Moorman Avatar
          Joe Moorman

          I suppose you could raise the polymer content so high that the mortar was compromised in density or compressive strength or some other property, but following manufacturer instructions should be enough to prevent those kind of issues.

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