Putting an air filter on your compressor output line will result in drier air feeding onto your Sand Blasting Machine. Normal regulator do normally have an air trap attached to them to collect water in the air but this doesn’t really stop much of the moisture.
If you get an excess of water in your abrasive it gets gluggy and won’t want to mix properly with the air flow resulting in irratic abration flow and possible blockages. So it’s a good idea to invest in a black box filter which will go along way to preventing this from happening.
Our trophy shop has a black box air filer in the middle of the air line that connects the compressor to the Pressure Pot. Inside the black box is a filter that looks just like a dunny roll and infact each week Bronwyn, our diligent maintainance person replaces the filter with an actual toilet paper roll and lets the original dry out. After another week she swaps the rolls around and lets the toilet roll dry out. You can probably use the same toilet roll for a couple of months using this alternating method. Look in the Yellow papers under compressors for suppliers of airline filters