BIZOMAT MAKEOS · Fabrication
Coating Job Estimate (Coats, Material, Thinner, Labour, Film)
How much coating, thinner and labour does this paint or powder job take for all its coats, what does it cost per square metre, and is the wet film within the sag limit?
Estimate of a coating job: theoretical and practical coverage and quantity per coat from the dry film thickness, volume solids or powder density and transfer efficiency (as the coating coverage tool), the quantity for all coats, thinner added, the wet film thickness to apply per coat against your sag limit, labour hours from the application rate, and cost in total and per square metre.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Coating | choice | Liquid paint or powder. |
| Area to coat | m² | Surface area to coat. |
| Dry film thickness per coat | µm | Dry film thickness for each coat (from the specification). |
| Number of coats | Number of coats of this product. | |
| Volume solids (liquid) | % | Volume solids of the paint from its data sheet. |
| Powder density (powder) | g/cm³ | Density of the powder. |
| Transfer efficiency | % | Share of the coating that ends up on the work (spray method and part shape). |
| Coating price per litre or kilogram | $ | Price of the paint per litre or powder per kilogram. |
| Thinner added (liquid) | % of paint | Thinner added as a share of the paint volume (liquid only). |
| Thinner price | $/L | Price of the thinner. |
| Application rate per coat | m²/h | Area one painter covers per hour for one coat. |
| Labour rate | $/h | Labour rate. |
| Largest wet film per coat (sag limit) | µm | Largest wet film the paint holds on a vertical surface without sagging (from the data sheet). |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Coating
- What it is
- Whether the coating is a liquid paint, costed by the litre from its volume solids, or a powder coating, costed by the kilogram from its powder density.
- Units and format
- Choose one of 2 options from the list: Liquid paint; Powder coating.
- Example
- The form opens with “Liquid paint” selected as a worked example. Choose the option that matches your case.
- Get it right
- Liquid uses volume solids, thinner and the wet film check; powder uses powder density and ignores those fields.
What this means: Area to coat
- What it is
- The total surface to be coated, counting every face that receives paint or powder.
- Units and format
- Enter a number in m²: square metres. The form accepts 0.000001 m² to 10000000 m². Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 50 m² as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Material and labour scale directly with area.
- Get it right
- Include both sides and edges where coated; the tool assumes flat-surface coverage, so allow extra for complex or rough parts.
What this means: Dry film thickness per coat
- What it is
- The cured film thickness specified for each coat, as read with a dry film gauge after curing.
- Units and format
- Enter a number in µm: micrometres (µm, microns). The form accepts 1 µm to 2000 µm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 75 µm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Coverage falls in inverse proportion, so material quantity and cost rise in step with it.
- Get it right
- Per coat, not the total system thickness; the total is this times the number of coats.
What this means: Number of coats
- What it is
- How many coats of this product are applied over the whole area.
- Units and format
- Enter a plain number with no unit. The form accepts 1 to 10. Use a whole number. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Material, thinner and labour all scale with the number of coats.
What this means: Volume solids (liquid)
- What it is
- The percentage of a liquid paint’s volume that remains as dry film after the solvent evaporates, from the product data sheet.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 5% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 60% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Higher volume solids increases coverage and lowers the wet film needed.
- Get it right
- Use volume solids, not weight solids; they are different numbers on the data sheet. Only used for liquid paint.
What this means: Powder density (powder)
- What it is
- The density of the powder coating from its data sheet, used to turn the film volume into kilograms of powder.
- Units and format
- Enter a number in g/cm³: grams per cubic centimetre (1 g/cm³ = 1000 kg/m³). The form accepts 0.5 g/cm³ to 5 g/cm³. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1.5 g/cm³ as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A denser powder covers fewer square metres per kilogram, so more is needed.
- Get it right
- Only used when Powder coating is selected.
What this means: Transfer efficiency
- What it is
- The share of the sprayed paint or powder that ends up on the part; the rest is overspray, line losses and residue.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 5% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 65% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Practical coverage scales with it, so a lower efficiency raises material quantity and cost.
- Get it right
- Calibrate it from actual consumption on similar jobs rather than the theoretical figure.
What this means: Coating price per litre or kilogram
- What it is
- The purchase price of the coating per litre for liquid paint, or per kilogram for powder, matching the coating type selected.
- Units and format
- Enter a number in $: an amount of money; use one currency for every money input. The form accepts $0 to $10000. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with $25 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use the price of the product as bought; thinner is priced separately below.
What this means: Thinner added (liquid)
- What it is
- The volume of thinner added to the paint to bring it to spraying viscosity, as a percentage of the paint volume.
- Units and format
- Enter a number in % of paint: % of paint. The form accepts 0 % of paint to 50 % of paint. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10 % of paint as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Only used for liquid paint. It adds thinner cost and raises the wet film you must apply for the same dry film.
What this means: Thinner price
- What it is
- The purchase price of one litre of the thinner or reducer added to the paint.
- Units and format
- Enter a number in $/L: money per L. The form accepts $0/L to $1000/L. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with $8/L as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Only liquid paint jobs use this.
What this means: Application rate per coat
- What it is
- The area one applicator can coat in an hour for a single coat, including handling and moving around the part.
- Units and format
- Enter a number in m²/h: m²/h. The form accepts 0.000001 m²/h to 10000 m²/h. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 20 m²/h as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Labour hours fall in inverse proportion to it.
- Get it right
- Base it on timed past jobs with similar parts; it is per coat, and the tool multiplies by the number of coats.
What this means: Labour rate
- What it is
- The cost of one hour of applicator time, including wages, on-costs and any booth overhead you charge by the hour.
- Units and format
- Enter a number in $/h: money per hour. The form accepts $0/h to $10000/h. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with $60/h as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Largest wet film per coat (sag limit)
- What it is
- The largest wet film thickness the paint can take in one coat before it sags or runs, from the product data sheet or trials.
- Units and format
- Enter a number in µm: micrometres (µm, microns). The form accepts 0.000001 µm to 5000 µm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 200 µm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Only checked for liquid paint; it is compared with the wet film needed, which includes the thinner.
Method and formulas
- Liquid: theoretical coverage = 10 × volume solids ÷ DFT (m²/L); powder: 1000 ÷ (density × DFT) (m²/kg); practical = theoretical × transfer efficiency (as the coating coverage tool).
- Quantity per coat = area ÷ practical coverage; total = per coat × coats; thinner = paint × thinner share.
- Wet film (liquid) = DFT × 100 ÷ volume solids × (1 + thinner share).
- Labour = coats × area ÷ application rate.
- Example: 2 coats need 19.231 units and 5 labour hours, about 15.923 per m²; apply 137.5 µm wet.
Limitations
- Flat-surface coverage; rough, profiled or complex steel uses more.
- Excludes surface preparation, masking and curing time.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Quote a painting or powder-coating job
- Order paint and thinner for a project
- Set the wet film gauge reading for the painter
Who it is for
- Estimators
- Coating inspectors
- Fabrication supervisors
What you get
- Coverage and quantity per coat and in total
- Thinner, wet film thickness and labour
- Total cost and cost per square metre
Interpreting the result
- Transfer efficiency is the biggest lever on material cost: electrostatic or airless methods raise it.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1500–1516. Topic reference; no source tables or recommended settings are reproduced.
Learn the Concepts Behind This Tool
These BIZOMAT Library readings explain the method this tool uses, with worked examples.
Useful alongside · BIZOMAT original book
Electrostatic powder coating
In Electrostatics in the Factory by the Numbers
What it covers: How a corona gun charges powder, why charged powder wraps round an earthed part, what causes back-ionisation and thin inside corners, and how transfer efficiency drives powder cost.
BIZOMAT tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
Open the Coating Job Estimate (Coats, Material, Thinner, Labour, Film) calculator