I don’t mind admitting it… I love glue. I have at least six different kinds in the cupboard at any one time, and PVA is a can’t-do-without staple. I’ve used it for all manner of creative, practical and DIY projects. It’s low cost, safe, easy to use and incredibly handy. But what is PVA’s secret? What lies behind this seemingly simple product that makes it such a useful piece of your wood finishes kit… what is PVA glue?
What is PVA?
What is PVA glue made from? Our first stop is Wikipedia. Here’s what it says about PVA:
“PVA is a rubbery synthetic polymer with the formula (C4H6O2)n. It belongs to the polyvinyl esters family with the general formula [RCOOCHCH2]. It is a type of thermoplastic. Polyvinyl acetate is a component of a widely used glue type, commonly referred to as wood glue, white glue, carpenter’s glue, school glue, Elmer’s glue (in the US), or PVA glue.”
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PVA glue facts
Polyvinyl acetate, PVA’s main chemical component, was discovered by the German Fritz Klatte in 1912. The resulting glue doesn’t give off smells or dangerous fumes and is perfectly safe to handle with bare hands.
As well as ‘real’ wood you can use it on plywoods, chipboards and MDFs. It can be used as a high performance sealer, primer, bonding agent and dust proofer.
PVA sets when there’s good air circulation, and dries fastest at room temperature. You get the strongest seal when you clamp the pieces being glued. It’s quick drying with a very high bond strength.
The yellow exterior version of PVA is often called Carpenter’s Glue… but it’s still PVA. In fact, there is a bewildering array of specialist PVAs but the formula is much the same.
PVA is flexible, permanent and only toxic if you eat it. It has a neutral pH value.
PVA is water soluble. You can add water to thick glue yourself to create a thinner, less gloopy one. It’s best to add water to the glue (not the other way around) a small amount at a time and stir it well, to make sure you don’t over-dilute.
“This glue is now very popular and in many opinions it is the best timber adhesive available because it dries clear, it’s very easy to apply and has super strong holding strength on wood.
They can creep over time but a tight joint helps to prevent that. Because of its many great features Polyvinyl Acetate is excellent for bonding woodwork joints together or as a furniture and carpentry adhesive.
Polyvinyl Acetates are very versatile and are relatively fast drying but excess glue must be wiped away after applying or it is very difficult to remove when dry.
Polyvinyl Acetate glues are available in white and yellow and are relatively inexpensive compared to most glue, they also have a reasonably long shelf life.
The white one is better for interior use because moisture weakens it over time and the yellow is better for outdoor use because it is water resistant but it doesn’t dry completely clear.”
“Most woodworkers today use the white wood glue, PVA. This provides a strong, and as far as we know, durable joint. The only glues that have really been tested by time are the animal glues and natural resins and gums. These are likely to be affected by heat and damp, and the animal glues, being rich in protein, are an invitation to insects and moulds if there is moisture present. Although some PVA glues are advertised as suitable for outdoor use, it is best to use a formaldehyde resorcin.
One possible drawback with PVA is that if you are gluing oak (Quercus robur), it may react with the tannin in the wood and go black, even staining surrounding wood if the surplus is not wiped off immediately.”
Plus, here’s a Youtube video about applying PVA glue:
PVA glue uses
What is PVA glue used for? As an emulsion, soluble in water, it is particularly useful for glueing porous materials, particularly for wood, paper and cloth. It doesn’t contain solvents and acts as a useful consolidant for porous building materials like sandstone. PVA adhesive is flexible, delivers a very strong bond and, unlike many polymers, it is not acidic. PVA wood glue is most often used:
- as a wood adhesive
- as a paper, fabric and leather adhesive
- in bookbinding
- in arts and crafts, for example mosaic
- as envelope adhesive
- as wallpaper glue
- as a drywall primer
- as a filler, by adding sawdust to it
A mixture of 50/50 PVA and water makes a very good sealant for plaster, preparing it for painting or wallpapering. It can also be used as a non-waterproof interior varnish, perfect for papier mache projects.
7 steps to using PVA to glue wood
PVA is a low cost, water-based, non-toxic way to glue wood to itself. Wood glue is a particularly strong version of ordinary PVA, ideal for heavier jobs. It dries completely clear but you can also buy pre-coloured versions that are less visible on wood surfaces.
- Squeeze the glue onto the surface of both of the bits of wood you want to glue together
- Remove any excess or spills immediately using a damp cloth
- Use either a specialist plastic spreader or a brush to spread a thin coat of glue over the surface of both pieces of wood
- Push the pieces together, rubbing the surfaces from side to side to remove trapped air and make sure the glue spreads evenly
- Grab a G-clamp or two and clamp the pieces securely
- Leave it for 24 hours before taking the clamps off
- Sand off any dried excess glue
The disadvantages of PVA glue
- Various fungi, algae, yeasts, lichens and bacteria can break down and degrade polyvinyl acetate
- PVA shouldn’t be allowed to freeze because it breaks up the polymer, which makes the glue useless
- You can’t varnish over PVA…but you can paint over it
- It takes 24 hours for the bond to achieve full strength
- It is not fully waterproof
How to remove PVA?
To get PVA off wood, sand it. If you get it on your clothes, a couple of warm washes should remove it. If it gets on your carpet, scrub it with warm water then Vax it up.
The most impressive PVA story on the planet?
I used PVA to varnish a decorated ceramic bowl, which I embellished with coloured papers and fabrics. It has been out in the garden for eight years through some of the worst winters and hottest summers on record, and it is still going strong. The surface goes a little milky in wet weather as the glue absorbs water and turns back into something sticky, but that’s about it. So while it isn’t supposed to be frost or water proof, under some circumstances PVA seems to be more or less indestructible.
Do you have a thrilling PVA tale to tell? If so we’d love to hear it!
Have a question about PVA Glue and its uses?
If you have a question about PVA Glue and its suitability for a project, give our resident experts a call who are on hand to provide free help and advice.