In another instalment in his ‘Products I have found useful’ series, Norman Holtzhausen features Duralac, now formulated in green.
Every boat that operates in or near salt water has a corrosion challenge. This is true whether the boat is brand new or, as in my case, more than 35 years old.
Every time a screw or bolt contacts another type of metal there is a potential for galvanic corrosion and future problems. This can also affect fibreglass, plastic or wooden boats, although they obviously have fewer points of contact between different metals than do aluminium or steel hulls.
The best way to reduce the possibility of issues arising in the future is to insulate the junction between unlike metals. Galvanic corrosion requires both an electrolyte between the different metals and an electrical connection between them, and if either of these is missing then the cycle cannot start. It is also usual practice to apply a form of setting compound to ensure the fastening does not come free over time from vibration or use. And the industry standard for this purpose is Duralac.
The product is a free-flowing paste that can be applied directly from the tube or with a small brush. It is easy to apply and air-dries to lock the fastening in place. Experienced boaties will remember Duralac as a bright-yellow, thick liquid that was liberally applied to the screw or bolt before it was assembled. Duralac has been on the market for nearly 100 years, and yellow-stained fingers were a common hazard for anyone fixing items to the hull. The bright-yellow colour was also highly visible, although it faded over time.
However, the formulation was reviewed a few years ago to remove the extremely toxic barium chromate component, which gave the product that distinctive bright-yellow colour. The new version has been tested and proven to be even more effective than the original while also being less toxic to the environment. It is now a pale green that is also less visible when freshly applied.
Since it sets hard, Duralac is not ideal for fixings that need to move or require some flexibility. However, it is the go-to for anything that needs to stay in place, and there is no question about its effectiveness. Only a small amount is needed on each joint and a single tube has pretty much done my whole boat. It also has a very long shelf life, and as long as the tube is properly closed each time it is used, the remainder will remain viable for years.
Available from all marine chandlers.
