Different materials and coatings call for different pressures or blasting distances. Thick metal can handle a lot of pressure, while sheet metal could be dented by using too much pressure. Simple paint may come off nicely with the nozzle far away, while tough undercoating may come off better with the nozzle closer.
The distance you hold the blast nozzle from the material affects the harshness and speed of the blast and changes the “blast pattern” size. If you hold the nozzle too far away, the blast pattern will be big, but the coating will come off too slowly. If you hold the nozzle too close, the coating will come off quickly, but the blast pattern will be small. With a tiny blast pattern you’ll have to move your arms a lot more to cover some area, which is inefficient. The best things is to find a nice balance between blast pattern size and removal speed.
As you blast more things, you’ll start to get a feel for what a material can handle, and you’ll adjust your blast distance instinctively. Watch the video above to learn the pressure ranges for the most common materials. The table below also has this information in written form.
These are approximate guidelines only, experiment until you find the optimal technique. Different coatings will also require different techniques, and it’s really just common sense and experimentation that will guide you. The closer the nozzle is to the blast surface, the smaller the blast pattern, the harsher the effect and the faster a coating will be removed. Until you get a feel for it, start far away and come in slowly to insure you don’t cause damage to the substrate.
| Material | Fiberglass Boats | Brick Walls | *Hoods and Trunks | Metal Auto Bodies | Thick Aluminum | Thick Steel |
| Blast Pressure | 70 PSI | 100 PSI | 70 PSI | 100-120 PSI | 120-150 PSI | 150 PSI |
| Blast Distance | 18-24 In. | 18-24 In. | 12-14 in. | 12-14 In. | 12-20 In. | 10-14 In. |
| Blast Pattern | Large | Large | Meduim, 20º angle. | Medium | Medium-Large |
Medium |
* When blasting hoods and trunks, be careful not to separate the bracing on the underside of the hood or trunk from the sheet metal. The bracing is the only thing that keeps the metal in the desired shape.
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