A thermosetting size applyable to paper in a size press and curable at a temperature not in excess of about 280°F for 10 seconds is disclosed.

The coating may be applied to the substrate during manufacture of the substrate, for example the coating may be applied to paper using a size-press machine during its manufacture.

Watermarked paper, preferably shadow-watermarked paper is produced in conventional manner and then size-press dyed using a pigment dyestuff composition.

The coater (18) can coat a web (26) directly or a moving roll surface (26' or 27') as in a film coater or size press.

The hydrophilic plasticizer, preferably comprising diethyl citrate, is avantageously added in a size press wetted with an aqueous solution containing the plasticizer subsequent to the fourdrinier machine.

The formulation is a low solids coating that can be applied on the size press of a paper machine, eliminating the need for a post-machine coating process.

In the procedure, the web (Win) coming from the pre-drying section of the paper machine is surface-sized on both sides in one or several size press nips (N1a; N1b; N1, N2).

The Size press compositions contain at least one non-reactive cationic surface sizing agent at least one reactive sizing agent, at least one promoter resin, at least one binder, and water.

The size press apparatus includes a first roll for rotation about a first rotational axis, the first roll defining a first peripheral surface which is disposed spaced and parallel relative to the first rotational axis.