Blu-tack is a reusable putty-like pressure-sensitive adhesive produced by Bostik, commonly used to attach lightweight objects (such as posters or sheets of paper) to walls or other dry surfaces. Traditionally blue (blu), it is also available in other colours.
The composition of Blu-Tack is a manufacturing secret but is described as a synthetic rubber compound without hazardous properties under normal conditions. It can be swallowed without harm and is noncarcinogenic. It is non-soluble and is denser than water. The material has a flash point of 93 °C / 200 °F, at which it releases carbon dioxide, carbon monoxide, water vapour, oxides of nitrogen, and toxic fumes.
In 1970, laboratory researcher Alan Holloway was working for sealant manufacturer Ralli Bondite of Waterlooville, England. Ralli Bondite was a wholly owned subsidiary of G & L Ralli Investment & Trustee Co. Ltd. Holloway inadvertently produced a product that was useless as a sealant, but pliable and semi-elastic. This novelty product was demonstrated by Ralli Bondite management to visiting executives from another sealant and adhesive manufacturer, as a means of wall mounting notices. There was no need for secrecy about the formula, as it was of no use for a gun-grade mastic, the main product of Ralli Bondite. Initially the potential of this material was not fully recognised, but later Bostik commenced research into the development of what they were eventually to launch as Blu-Tack. In its conceptual stage Blu-Tack was white, but was coloured blue because it is actually blue. 
In the United Kingdom in March 2008, 20,000 numbered packs of pink Blu-Tack were made available, to help raise money for Breast Cancer Campaign, with 10 pence from each pack going to the charity. The formulation was slightly altered to retain complete consistency with its blue counterpart. Since then, many coloured variations have been made, including red and white, yellow and a green Halloween pack.
Similar products of various colours are made by many manufacturers, including:
- "Tack-it" by Faber-Castell
- "Poster Putty", "Tac 'N Stick", "Ticky Tack", "Sticky Tack", "Patafix" and "White Tack" by German company UHU
- "Sticky Stuff" and "Fun-Tak" by Henkel brands Pritt, Loctite and LePage
- "Poster Tack" and "Elmer's Tack" by Elmer's.
They are also sold under the generic names "adhesive putty" and "mounting putty".
The generic trademark or common name for mounting putty varies by region:
- "Power Tack"
- "Overtictack" in many parts of the US and Canada.
- Prestik in South Africa
- "Patafix" in France and Italy (phonetic abbreviation for "pâte à fixer", "fastening dough" in French).
- "Kennaratyggjó" (teacher's chewing gum) in Iceland
- "Elefantsnot" (elephant's snot) in Denmark
- "Häftmassa" (attachment mass) or "kludd" in Sweden
Like all poster putties, Blu-Tack provides an alternative to the artist's traditional kneaded eraser, having a superior grip and plasticity. Blu-Tack can be finely shaped and worked into even very small areas. Like kneaded erasers, it can be stretched and kneaded to freshen its working surfaces.
Blu-Tack is also used for sculpture. In 2007 artist Elizabeth Thompson created a 200-kilogram sculpture of a house spider using Blu-Tack over a wire frame. It took around 4000 packs and was exhibited at London Zoo. Other artists have created works from the material including stop-motion animation.
Blu-Tack acts as an excellent damping agent for sound and vibration applications, due to its low amplitude response properties.
- "Blu-Tack". H2G2. Retrieved 27 January 2012.[not in citation given]
- "Blu Tack and how it is made". Frequently Asked Questions. Bostik Australia. 2005. Archived from the original on 2005-12-10. Retrieved 2006-01-10.
- "Daily Express | UK News :: Blu-Tack goes pink for charity". Express.co.uk. 2008-03-04. Retrieved 2009-07-28.
- By tulpastudios Elizabeth Thompson+ Add Contact. "Elizabeth Thompson Blu tack spider | Flickr - Photo Sharing!". Flickr. Retrieved 2012-01-31.