Polyvinyl acetate (PVA, PVAc, poly(ethenyl ethanoate): best known as wood glue, white glue, carpenter's glue, school glue, Elmer's glue, Weldbond (to name a few in the US) is an aliphatic rubbery synthetic polymer with the formula (C₄H₆O₂)ₙ,.
WeldBond is the most widely used and preferred by mosaic artists. As we go forward in this section, Weldbond is the PVA product that we will be referring to and the one recommended for interior mosaics,.
Characteristics
- Non-Toxic, safe for children, and fume-free.
- Weldbond’s “body” is thicker than other PV glues, when used to adhere your “tile” to the substrate there is less “floating” than other white PVA Brands.
- Dries clear. Great when bonding transparent and semitransparent materials such as glass to glass. (One thing to keep in mind when using WeldBond for glass on glass. It goes on white and dries to clear and can sometimes take weeks if your tesserae are large (over 1/2"). Limited airflow + larger tesserae = very long dry times and inconsistent clarity.
- It may be used as a sealer on porous substrates such as wood and MDF. Mix 5 parts water to 1 part WeldBond. Paint the surface with this mixture and allow it to dry.
- Bonds to most anything. Glass, marble, terra-cotta, wood, Formica, etc. It is always beneficial to score (rough up) smooth surfaces to give them a little tooth. This process creates a better bond when using most types of adhesives. You can scratch them with a sharp object or sand them with coarse-grade sandpaper.
- Cleans up with water while it is still in its "white" stage.
- High temperatures and low humidity will speed up the curing process. The cure is complete once it has turned clear. It will continue to strengthen over time.
- Caution! Weldbond can create an unwanted barrier when used to glue tesserae to mesh (indirect mesh method). This is discussed on another page.
- It can be applied directly from the bottle. A popular method of application is to work from a small snap lid container and paint it on with a small paintbrush. This allows the glue to tack up a bit while in an open container.
- When using it to adhere glass to glass, the lack of exposure to air will lengthen the dry time. The larger the pieces being glued, the longer it will take for the glue to cure clear. I don't reccomend it for pieces over 1/2" square.
Read the manufacturer's instructions! For further info about Weldbond that is not answered here, see the manufacturer's specifications available at Frank T. Ross.
Here is a great video demonstrating the Direct Method using WeldBond. It is a perfect way to start your mosaic journey.
