Adhesives for Mosaic Mannequins and Fiberglass Sculptures

We never have to worry about evaluating new adhesives in our work because we use conventional mosaic backers like plywood (indoors), concrete backer board, stone slabs and masonry walls. This means we always use Weldbond (a white PVA adhesive for dry indoor mosaics) and thinset mortar for everything else.

But what if you are wanting to put a mosaic on a plastic mannequin or a fiberglass sculpture or some other novel backer?

Well, these backers were made to be light weight, and so it doesn’t make sense to use thinset, which is a type of concrete, and Weldbond does not bond at all to most plastics.

Silicone and Epoxy

Many people report using silicone-based adhesives and epoxies on plastics with good results, but there are several reasons to test whatever adhesive you select on your particular backer before investing time attaching very many tiles.

Reasons to Test Your Adhesive

Plastic Ain’t Plastic

There are many different types of plastics. The information you read online might say the product works well on plastic or bowling balls or whatever, but chances are that whatever plastic you have isn’t exactly the same as what the author used in their project, especially if you are using something found at a thrift store or yard sale and possibly several decades old.

Delamination of Composite Materials

The problem might actually be within the substrate and not the glue per se. For instance, testing might reveal that your plastic is actually a composite material with a thin outer layer that pulls off relatively easily when something is glued to it.

Glues Can Go Bad

What if the problem is with your particular container of glue? Specialty adhesives have shelf lives and expiration dates and can sometimes be ruined by exposure to heat or cold.

Scrape Test

The easiest way to test an adhesive is to put a small bead or dot of adhesive in an out-of-the-way place on your backer and try scraping it off a few days later with a paint scraper or putty knife. Remember to use common sense and not damage your sculpture. If the bead of adhesive won’t come off, don’t keep banging on it with the scraper until you come away with a big chunk of the substrate or crack your sculpture. Instead, use sandpaper to sand the adhesive down.

To make your test bead, you will also want to rub the wet adhesive onto the surface to make sure that the bead of adhesive has actually made intimate contact with the surface and isn’t just sitting on top superficially. You don’t have to smear it flat. It can still be a small bead.

I recommend putting two or three beads of adhesive in the test area to make sure that you have at least one that has good contact. If the adhesive fails the test, you want to know it failed because the adhesive isn’t meant for the material, not because you didn’t apply it very well. For the same reason, you will want to make sure that you prepare the surface before testing.

Surface Preparation

Before applying glue, you need to make sure the surface is clean and free of dust and oils. Most molded plastic surfaces are fairly smooth, so you will also want to lightly scuff it with a medium-grit sandpaper. However, you shouldn’t skip cleaning the surface before sanding it. If there are oils or contaminants on the surface, it is possible for them to migrate down to the freshly exposed material as you are sanding. The sandpaper gets contaminated and then contaminates the new material underneath.

I use dish-washing detergents for cleaning applications like this because they wash away cleanly. Solvents like alcohol might be more effective for lifting grease with less scrubbing, but they also run the risk of being absorbed by the material being cleaned. Probably not, but it’s safer to assume the worst when using a base of unidentified materials.

Which Brand to Use?

Consider brands like Loc-Tite, DAP and Permatex. Loc-Tite makes a variety of adhesive products in addition to epoxies and silicone adhesives, so make sure you don’t buy one of their super glue (cyanoacrylate) products. Cyanoacrylate bonds are strong but tend not to last as long because they are brittle.

Gorilla Glue is a tougher and more impact resistant cyanoacrylate adhesive, and it does have a lot of fans, but we have not used it. I would be interested in learning more about how it ages. If the tiny rubber particles that give Gorilla Glue its toughness were to oxidize over time and dry rot the way rubber does, then I would have serious doubts about using it in art meant to be durable.

Going to the adhesive aisle of a building material store and reading a few labels is a good way to find a few candidates and compare them side by side based on manufacturer recommendations. Usually the packaging will have a list of materials the adhesive will work on. Online shopping might be less useful in this regard because the product descriptions are often fairly brief, but the flip side is you can read product reviews.

HOWEVER, no matter how much of that type information you gather, make sure you test the adhesive on your particular plastic/fiberglass backer before committing time on the actual tiling.







17 responses to “Adhesives for Mosaic Mannequins and Fiberglass Sculptures”

  1. […] Here is the article he wrote on adhesives for mosaic mannequins and fibreglass sculptures.  Check it out here […]

  2. […] Here is the article he wrote on adhesives for mosaic mannequins and fibreglass sculptures.  Check it out here […]

  3. Janette Avatar

    Hi there. After reading various articles I know to glue my glass mosaics on with silicon. How do I go about grouting inbetween? This is a fiberglass or plastic mannequin

    1. Joe Moorman Avatar
      Joe Moorman


      I’m not 100% certain because I’ve not made a mosaic on a mannequin, but I suspect that one of the new epoxy grouts would be the best way to go (instead of traditional grout) because it should adhere better and have more strength.

  4. Stacia Goodman Avatar

    Hello. I’m hiring a fiberglass-form making company to create a custom heart form for me. Do they need to sand and prime the form first (only to have me “rough” it up again with sandpaper), or can I have the company skip the sanding and priming step? The pre-sanded/pre-primed surface looks like a slightly bumpy woven lattice of fiberglass. Also, is thin set adhesive a big no-no on fiberglass, due to low adhesion? I would so appreciate your help!

    1. Joe Moorman Avatar
      Joe Moorman

      Hi Stacia,

      We aren’t the best people to ask because we don’t use fiberglass backers, but I agree that it would be best to skip the finished surface coating and glue directly to the rough fibers in resin.

      The best people to ask what adhesive to use to glue to the rough form is the people who are making the form. It might be silicone. That would be the first thing I would try.

      I hope this helps!

  5. Anne langdon Avatar
    Anne langdon

    It is great to get some info on mannequins adi have been given one & would love to have it outside

    1. Lynn phillips Avatar
      Lynn phillips

      I have covered my plastic mannequin in metallic tape (used in insulation and ducting)
      Can I still mosaic on top and which glue would you suggest

      1. Joe Moorman Avatar
        Joe Moorman

        Hi Lynn,
        I suspect something like our GE Silicone II would be required to adhere to metal tape.

  6. Fran Avatar

    I have an old mannequin whose outer layer is flaking off. How can I prepare it for mosaic?

    1. Joe Moorman Avatar
      Joe Moorman

      Hi Fran,

      That all depends on the particular mannequin. If there is a solid layer underneath, then you would want to take the flaking layer off. If there isn’t, you should consider wrapping it in gauze and Weldbond adhesive to create a thin but tough skin.


  7. Kim Avatar

    I recently started mosaicing on a plastic mannequin. I cleaned and sanded it and have glued the tiles on with mosaic glue. It is not yet completed and is not ready for grouting. I decided to alter the design and lifted and removed some tiles. They were easy to remove. Is this a bad sign that they came off readily or is this normal?

    1. Joe Moorman Avatar
      Joe Moorman

      Hi Kim,
      That is bad, and it is an example of why it is a good idea to test an adhesive on a substrate before proceeding with a mosaic. Conventional mosaic glues do not adhere to plastic.

      1. Kim Avatar

        So what should have been used? I read your article on glue but did not realise it should not be able to come off at all. I read it and did test beads- it adhered and did not readily come off but when I wedged a blade under the tile I could lift it. I have not seen Loc-Tite, DAP OR Permatex in Australian stores.
        Can it be saved or does everything need to be removed and laid again.Kim

        1. Joe Moorman Avatar
          Joe Moorman

          Hi Kim,

          That is bad. None of it will stay glued to the plastic. The purpose of the article was that Weldbond doesn’t bond well to plastic. Instead of looking for North American brand names, look for silicones and epoxies and tarry construction adhesives. Their will be products there that can bond to plastics. Probably SE Asian brands.

          I hope this helps.

  8. Nushi Avatar

    The mannequin I got is made of plastic material and cover with fabric. Can I mosaic directly on the fabric or I need to strip the fabric and work on the plastic?

    1. Joe Moorman Avatar
      Joe Moorman

      I would remove it if possible.

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