~One manâ€â„¢s opinion / observations
Layering:
By applying another product on top of one that has already cross-linked you can increase its density (up to a point) the thin film of product that's applied isn't really another layer. Two to four cross-linked (cured) applications are usually considered optimum
One thing that will negate the applied product density is lack of clarity, the base coat (that contains the vehicleâ€â„¢s colour) is covered / protected by a clear coat of urethane paint, which as well as providing protection is clear to enable the paint colour to show through and provide the colour with depth. Any product applied on top of the clear coat needs to be optically clear (transparent) otherwise both the paint colour and its depth of shine will be muted
Solvents provide a lubricant and aid the adherence process by working their way into the microscopic gaps and valleys of the previous `layer' softening it, providing each subsequent applications carrying agent (solvent, oils silicones or emulsion) are not so concentrated that they degrade or remove (as in the case of a cleaner wax) what has been previously applied.
The carrier system (solvents) allows the product to fill and level the paint film surface to produce a flat surface (this flat level surface is more pronounced with polymers due to their molecular alignment characteristics). This level surface optimises the paint film surface's desired optical properties (i.e. surface reflectance, clarity, gloss, and depth of shine)
Also be aware that the both the product and the foam pad may be non-abrasive, but application pressure if not kept to an absolute minimum and using use a very light and even pressure, may re-introduce surface marring and/or removal of the previously applied product.
~Hope this helps~
Knowledge unshared is experience wasted [each one / teach one]
justadumbarchitect / so I question everything/ JonM