Prepared by the FEVI Technical Department | Published 1 September 2026 | Last revised: 1 September 2026
Blasting correctly means achieving the required result without damaging the substrate, unnecessarily dispersing abrasive or making the process unstable. There is no single pressure, distance or angle suitable for every job: the parameters depend on the material, the layer to be removed, the abrasive, the nozzle, the available airflow and the subsequent finish. The most reliable method therefore starts from the result to be achieved, not from the machine.
Blasting correctly does not mean using maximum pressure
Increasing pressure makes the jet more energetic, but it does not correct an unsuitable abrasive, an undersized compressor, a restrictive air line or inconsistent technique. It can instead increase consumption, wear and the risk of deformation or erosion of the substrate. The correct setting is the one that achieves the objective consistently while retaining an adequate margin of control.
The pressure reading on a gauge near the compressor does not necessarily describe what is happening at the nozzle. Filters, separators, fittings, hoses that are too small or too long and worn nozzles all affect actual pressure and airflow. The machine, compressed air, abrasive and operator must therefore be considered as a single system.
The correct method in nine steps
1. Define the result and acceptance criteria
Before starting, establish whether the objective is to remove oxides, paint, mill scale or tenacious residues, or simply to create a uniform finish. Specify what will happen afterwards: painting, metallising, bonding, satin finishing, restoration or simple inspection of the component. Each subsequent process requires a different type of preparation.
- Required visual appearance and acceptable removal level.
- Surface profile compatible with the coating or subsequent process.
- Areas to protect: threads, seats, seals, machined surfaces and sensitive components.
- Tolerance for deformation, rounding, material loss or aesthetic changes.
- Inspection method and acceptance criteria agreed before treatment begins.
2. Identify the substrate, coating and contaminants
Steel, stainless steel, aluminium, wood, stone and composite materials react differently to impact. The layer being removed also matters: an elastic coating, a friable oxide and a mineral deposit do not require the same combination of parameters. Before treating unknown surfaces, collect information about the component, previous finishes and any substances that may be present.
3. Select the blasting system
| System | When it is suitable | Constraint to verify |
|---|---|---|
| Open blasting | Large areas, variable geometries, intensive removal and surface preparation | Containment, dust, residue collection and available compressed air |
| Recovery blasting | Localised operations where dispersion and restoration of the working area are critical | Recovery-head sealing against the geometry and continuity of extraction |
| Blasting cabinet | Moveable components, repetitive operations and control of abrasive recycling | Dimensions, visibility, separation and ventilation |
| Pre-dampening | Reduction of airborne dust in applications compatible with water | Moisture management, residues, corrosion and subsequent treatment |
| Automatic system | Repetitive production with defined parameters, times and handling | Tooling, coverage of component geometries and cycle validation |
The correct system is not necessarily the most aggressive one, but the one that combines productivity, accessibility, containment, required quality and repeatability. If the component can be placed in a cabinet, the process is often easier to control; if the item is fixed or very large, containment and residue management become central.
4. Select the abrasive and particle size
The abrasive's shape, hardness, density, particle size, friability and purity influence removal capacity, surface profile, finish, dust generation, recyclability and wear. An angular particle tends to cut and create profile; a spherical particle tends more towards uniforming or satin finishing. A coarser abrasive is not always more productive: it must flow consistently through valves, hose and nozzle and produce the required surface profile.
On stainless steel and sensitive alloys, abrasives or blasting circuits contaminated with ferrous material must also be avoided where such contamination is incompatible with the required result. If abrasive is recycled, fines separation, moisture control and contamination prevention become part of the process.
5. Check the compressor, air line and nozzle
The compressor must provide sufficient airflow to meet nozzle consumption at the actual working pressure, including any other connected users. Receiver size does not replace continuous airflow capacity. Damp or contaminated air can cause the abrasive to cake and produce inconsistent feed; restrictive pipework can create pressure drops even when the compressor is nominally adequate.
- Check the compressor's actual delivered airflow, dynamic pressure and duty cycle.
- Verify the internal diameter, length, bends, fittings and condition of the hoses.
- Drain condensate and check air separation, filtration and any drying system.
- Measure the nozzle's actual diameter: wear increases air consumption and alters the jet.
- Check valves, abrasive metering, remote controls and safety devices in accordance with the manual.
6. Prepare the working area, component and safety measures
Remove or protect items that must not be struck, stabilise the component and isolate the working area. Provide containment, ventilation or recovery according to the process; establish how abrasive and removed material will be collected. Operators must be trained and use the protective measures defined by the risk assessment, including protection for the respiratory system, eyes, face, hearing, body and particle impact.
7. Carry out a preliminary test
Select a representative, less visible area or a sample of the same material. Start with a conservative setting and change one parameter at a time. The purpose of the test is to establish the minimum effective combination and confirm that no deformation, excessive etching, staining, contamination or surface roughness incompatible with the subsequent process occurs.
| Parameter | If increased or decreased | What to observe |
|---|---|---|
| Jet pressure | More energy or more controlled action | Removal, consumption, deformation, wear and stability |
| Distance | More concentrated or wider jet | Uniformity, local aggressiveness and coverage |
| Angle | More direct impact or more grazing action | Surface profile, removal ability and risk at edges |
| Travel speed | More or less time on the same area | Coverage, over-treatment and differences in appearance |
| Abrasive feed | Richer or leaner mixture | Performance, consistency, visibility and consumption |
| Particle size | More pronounced or finer impact | Surface profile, finish and flow through the system |
Photograph the sample and record the machine, nozzle, abrasive, dynamic pressure, abrasive feed and operating technique used. For repetitive work, this reference reduces dependence on the operator's memory.
8. Keep the technique consistent during blasting
- Position the jet steadily and start it according to the machine instructions, without directing it towards people or unprotected components.
- Maintain the distance and angle established on the approved sample; correct your posture before quality begins to vary.
- Work with regular overlapping passes, avoiding pauses that concentrate the impact on one point.
- Treat edges, welds, cavities and shadow areas with a dedicated sequence: geometry changes the actual angle of impact.
- Periodically check dynamic pressure, abrasive flow, visibility, nozzle condition and hose condition.
- Stop the cycle if pulsating feed, loss of performance, moisture, abnormal noise or unexpected dispersion occurs.
9. Inspect and protect the result
The surface must be inspected before dust, condensation, rapid oxidation or contamination makes the result difficult to assess. On steel intended for coating, the visual preparation grade and surface profile must meet the specification; where required, residual dust, soluble contaminants and environmental conditions must also be checked. The interval between surface preparation and coating application must follow the specification and the coating manufacturer's instructions.
Residues must be removed using methods compatible with the process and risk assessment. Avoid redistributing dust using uncontrolled compressed air. Protect the prepared surface from contact, moisture and recontamination until the next process stage.
Guidance for the main materials
| Substrate | Common objective | Main precaution |
|---|---|---|
| Carbon steel | Remove oxides and coatings and create the required surface profile | Agree preparation grade, surface profile and permitted contamination with the protective coating system |
| Stainless steel | Uniform or prepare the surface without ferrous contamination | Use compatible and dedicated abrasive and blasting circuits where necessary |
| Aluminium | Remove finishes or create a uniform appearance | Limit energy and dwell time to avoid etching and deformation |
| Wood | Remove surface layers or enhance the grain | Start with a conservative test: species, moisture and fibre respond differently |
| Stone, brick and concrete | Remove residues or restore the appearance of the substrate | Assess cohesion, porosity, joints, salts and possible generation of respirable silica |
| Glass and sensitive materials | Satin finishing or controlled treatment | Precise masking and parameters validated on a sample |
These guidelines help define the preliminary test but do not replace a specification. For valuable components, layered materials or historic surfaces, the process must be validated on a sample and the specialists responsible for the item should be involved.
Checklist before, during and after blasting
| Stage | Essential checks |
|---|---|
| Before | Result defined; substrate identified; sample approved; area protected; air, abrasive, nozzle, hoses, extraction and PPE checked |
| During | Stable dynamic pressure; consistent flow; distance, angle, speed and overlap maintained; visibility and containment under control |
| After | Preparation grade and profile checked; dust and contaminants controlled where required; residues removed; surface protected; parameters and abnormalities recorded |
Mistakes that make blasting inconsistent
- Starting without defining the required result and judging the outcome only visually after the work is complete.
- Using more pressure to compensate for insufficient airflow, damp abrasive or a restrictive line.
- Selecting the abrasive out of habit or based on price while ignoring shape, purity and the required surface profile.
- Failing to measure nozzle wear and progressively losing jet stability while increasing air consumption.
- Working too close, too slowly or pausing on edges and thin sheet metal.
- Changing several parameters at the same time and being unable to determine which change improved or worsened the result.
- Recycling contaminated abrasive or abrasive containing excessive fines without checking separation and particle size.
- Ignoring residual dust, salts, condensation or recontamination before coating.
- Repeating parameters used on one material on a different substrate without carrying out a new preliminary test.
How to make the process repeatable
Repeatability begins with a simple process sheet. For each family of components, record the substrate and initial condition, objective, machine, abrasive and batch, particle size, nozzle and measured diameter, dynamic pressure, abrasive feed, indicative distance, angle, sequence and overlap of passes, processing time, final checks and photographs of the approved sample.
If quality changes, compare the recorded data before making adjustments. A reduction in performance may be caused by the nozzle, compressed air, moisture, abrasive feed, abrasive contamination, filter or operator technique. Changing one factor at a time makes diagnosis faster and easier to document.
Minimum process data to record
A short process sheet makes it possible to reproduce the approved sample and diagnose deviations. The fields should be adapted to the machine, material and inspections required by the job.
| Item | Data to record | Why it matters |
|---|---|---|
| Component | Material, dimensions, initial condition and protected areas | Makes batches and geometries comparable |
| Objective | Layer to remove, appearance, preparation grade, surface profile or finish | Defines the acceptance criteria |
| System | Machine, configuration, hoses, air treatment and extraction | Reconstructs the system conditions |
| Abrasive | Type, particle size, batch, condition and number of recycling cycles | Highlights wear, fines and contamination |
| Nozzle | Type, nominal diameter and measured diameter | Links air consumption to jet shape |
| Settings | Dynamic pressure, abrasive feed and machine parameters | Makes it possible to reproduce the operating point |
| Technique | Distance, angle, sequence and overlap of passes | Reduces variability between operators |
| Result | Final inspections, photographs, abnormalities, operator and date | Creates traceability and a reference for the batch |
How to select the FEVI configuration
To identify a suitable configuration, send FEVI photographs of the component and its initial condition, material, dimensions, layer to be removed, required final result, quantity or frequency of work, working environment and compressor data. Also specify whether the priority is productivity, finish control, reduced dispersion, abrasive recovery or integration into a production line.
This information makes it possible to compare open blasting, recovery blasting, blasting cabinets, pre-dampening and automatic solutions and to match the nozzle and abrasive to the air actually available. Selection therefore becomes a process decision rather than simply the purchase of a machine. Explore FEVI blasting systems to discover all the available technologies.
Frequently asked questions about how to blast correctly
What is the correct pressure for abrasive blasting?
There is no universal value. It depends on the substrate, residue, abrasive, nozzle and required result. Start with a conservative test and check dynamic pressure close to the machine or at the point specified by the manufacturer, not only static pressure with the circuit closed.
How far should I hold the nozzle from the surface?
The distance should produce a stable jet and uniform coverage on the specific material. Moving closer concentrates the action; moving farther away widens the pattern and reduces local energy. The distance should be validated on a sample and then kept consistent.
At what angle should I blast?
A more direct impact tends to transfer more energy and create surface profile; a more grazing action can help detach certain layers. Geometry and substrate alter the result, so the angle should be selected during testing and adapted for edges and cavities.
How do I choose the abrasive?
Start from the material, the layer to be removed, the required profile or finish, contamination risk, recovery system and safety requirements. Shape, hardness, density, particle size and friability must be compatible with both the machine and the required result.
How do I know whether the compressor is sufficient?
Compare the compressor's actual delivered airflow with nozzle consumption at working pressure and include pressure losses, other users and the duty cycle. Receiver volume alone does not demonstrate that sufficient air is available.
Why does the jet pulse or the abrasive come out intermittently?
Possible causes include moisture, condensate, incorrect abrasive feed, poorly flowing abrasive, blockages, worn valves, unstable pressure or an inadequate air supply. Stopping the cycle and diagnosing the problem helps prevent an uneven finish.
How can wood be blasted without damaging it?
A conservative test is required because species, grain, moisture and finish react differently. Use a compatible abrasive and particle size, controlled energy, consistent distance and rapid passes, checking the effect on the wood fibres.
Can aluminium be blasted?
Yes, but aluminium can become etched or deform more easily than a substantial steel component. The combination must be validated on a sample, limiting dwell time and aggressiveness and controlling contamination.
How can I achieve a uniform finish?
Use consistent abrasive, a nozzle in good condition and stable parameters. Maintain distance, angle, travel speed and overlap between passes, follow a consistent sequence and compare the result with the approved sample.
How should blasting be checked before painting?
Check the requirements of the specification and coating data sheet. On steel, the required checks may include visual preparation grade, surface profile, absence of residual dust and contaminants, and suitable environmental conditions before application.
Is wet blasting always better?
No. It can reduce airborne dust, but it introduces water and requires management of residues, compatibility with the substrate and coordination with the subsequent treatment. It should be selected when these factors can be properly controlled.
Which information does FEVI need to recommend a blasting machine?
Photographs, material and dimensions, layer to be removed, required result, quantity or frequency of use, working environment, restrictions on dispersion and compressor data. The better defined the sample and application, the more precise the selection can be.
Conclusion
Blasting correctly means controlling the entire process: required result, substrate, abrasive, compressed air, nozzle, operating technique, safety and final inspection. A preliminary test turns generic parameters into a setting suited to the actual application; recording the data makes that setting repeatable.
Talk to FEVI
Send photographs, material, dimensions, coating to be removed, required result and compressor data. The FEVI team can help identify the blasting system, nozzle and abrasive most consistent with the application.
