Method and apparatus for the production of composite sheet material and a sheet material produced thereby

A method of making a composite product including distinct layers of two different water-based curable compositions capable of bonding together on curing, the method comprising the steps of:

• depositing a first layer of a first of said curable compositions onto a base member while said first composition is wet and uncured and in a viscous state having adequate strength to support a second layer but capable of flowing under the influence of vibration;
• depositing directly and immediately onto said wet first layer a wet second layer of the second of said curable compositions without any prior treatment of the wet first layer other than levelling, the second composition being wet and uncured and in a viscous state but capable of flowing under the influence of vibration and the two layers meeting at an interface;
• temporarily creating a localised zone of fluidization extending through said wet second layer to the interface between the wet first and second layers by the application of vibration to a small localised area of the surface of the wet second layer to promote intimacy and subsequent bonding of the first and second layers, the first and second compositions remaining viscous outside the said localised zone of fluidisation;
• and allowing the first and second compositions to cure together to form the composite product.