You can select your traces and click on the Expose Copper button. If you select HASL or HASL lead-free  PCB finish then all exposed copper will be tinned with solder. The thickness of solder with the HASL finish is however only a fraction of a millimetre. To build up the solder thickness for higher current handling you will have to add solder by hand. Better options may be to: 1. ask for 2 ounce copper on the outer layers and; 2. to use the widest possible traces;  3. add Copper Areas to tracks (i.e. surrounding tracks with copper plane area) and; 4. use both sides of the board and even inner layers of a multilayer pcb.

Perfect.  Thanks!