There are 3 main used techniques to finish A1 smooth:
A1 Thix A
Add A1 Thix A to the A1 to thicken the A1 into a paste. Apply the thickened A1 paste with a spatula or putty tool. This creates a layer that you can finish within 1 hour with a slightly damp sponge for a smooth result. After drying you can work on the A1 object with (waterproof) abrasive pads or (waterproof) sandpaper.
A1 ATP Powder
A1 ATP Powder is a volume thickener. This allows the A1 to be thickened to filler thickness. Thicken the A1 with ATP Powder; with this A1 can be thickened to filler thickness. The ATP Powder can be added indefinitely, until the desired thickness is reached. This does, however, result in a less strong product when a large amount of ATP Powder is added. ATP Powder can only be used for indoor applications.
The application of A1 with ATP Powder goes well with for example spatula, palette, putty knife etc.
After drying you can if desired with waterproof abrasive pads or waterproof sandpaper further refine to an even smoother whole.
C-veil is a thin glass fleece finish. Apply C-veil to the still damp last layer A1. If the A1 is dry, first coat it with a layer of A1. The C-veil is very easy to tear, small pieces are easy to press, so you can achieve a nice smooth and seamless result. If desired, a second layer with C-veil can be applied. Like the A1 Triaxial fibre, the C-veil cannot be sanded.