If you go to the store and buy a tube of adhesive, chances are it’s going to be a clear solution. That’s great for when you want to glue something transparent together, but it does generally make it difficult to see where the adhesive is and how much you have used.Japanese company Kokuyo has come up with a solution to this problem, though. They’ve figured out a way to make their instant adhesive stay red for 3 minutes before turning transparent over the course of 10-20 minutes. By doing so, applying the adhesive and controlling how much use should be a lot easier because it is much more visible at the time of application. At the same time, you end up with a similar finish to traditional clear adhesives because it loses its color.Kokuyo has obtained a patent for the technique that allows the color change to happen. It involves the use of photocromic technology, which sees compounds that undergo a photochemical reaction included in the adhesive. So the adhesive remains red while protected in its container, but as soon as it comes into contact with light it starts changing color.Such a feature is both useful and highly marketable, so I expect a number of the big name adhesive brands to either try to get a license from Kokuyo or copy it and workaround the patent somehow.Japan’s National Institute of Advanced Industrial Science and Technology (AIST) may also take an interest. In February they announced a reusable adhesive that liquefies under UV light, but it didn’t dry to a transparent state. Maybe AIST and Kokuyo can join forces to create the ultimate is reusable adhesives.