ISO/TC 35/SC 12/WG 2 - Surface cleanliness

This document specifies a series of preparation grades for steel surfaces after removal/partial removal of water-soluble contaminants, rust, previous paint coatings and other foreign matter by high-pressure water jetting. The various grades are defined by written descriptions together with photographs that are representative examples within the tolerances for each grade as described in words. This document specifies both initial surface conditions and after-cleaning flash rust grades, also defined by written descriptions together with representative photographic examples. This document applies the cleanliness of the surface to its visual appearance. Consideration in addition to visual appearance is given to invisible contaminants and roughness or profile. Physical and chemical methods for testing for soluble salts and other invisible contaminants on the visually clean surface are found in the ISO 8502 series. The roughness or profile characteristics of the surface are found in the ISO 8503 series.

This document specifies a method of extracting, for analysis, acid soluble contaminants from a surface by use of flexible cells in the form of adhesive patches or sleeves which can be attached to any surface, regardless of its shape (flat or curved) and its orientation (facing in any direction, including downwards). The described method is suitable for use in the field to determine the presence of acid soluble contaminants before painting or a similar treatment. This document does not cover the subsequent analysis of the contaminants that have been dissolved off. Methods of analysis suitable for field use are described in other parts of ISO 8502 such as ISO 8502-5. This document is similar in procedure to, but not equal to, ISO 8502-6. The main difference is the solvent used and the subsequent analysis that can be performed on the extraction solution.

This document specifies a field method for the assessment of the surface density of various water-soluble salts on steel surfaces, before and/or after surface preparation, by conductometric determination. The individual surface densities of the salt composition like chlorides, sulphates, sodium, etc, cannot be determined by this method. This method assesses only contaminants that forms an electrolyte (ions) when in contact with water. These represent the greater part of the contaminants.

This document specifies a method of extracting, for analysis, water soluble contaminants from a surface by use of flexible cells in the form of adhesive patches or sleeves which can be attached to any surface, regardless of its shape (flat or curved) and its orientation (facing in any direction, including downwards). The method described is suitable for use in the field to determine the presence of water soluble contaminants before painting or a similar treatment. This document does not cover the subsequent analysis of the contaminants that have been dissolved. Methods of analysis suitable for field use are described in other parts of ISO 8502. NOTE The extraction method might give a false negative or not take all the water-soluble material off the surface because of: a) Soluble materials hiding in the crevices or under folds of metal; b) Soluble materials under corrosion layers, passivation layers produced by corrosion inhibitors, oil, grease, or other non-visible thin films.

This document provides guidance on the usage of analytical colorimetry to support visual assessment of surface preparation grades described in ISO 8501-1:2007, Clause 4. This document provides examples of applications where the use of a colorimeter or spectrophotometer can enable a quick and objective assessment of the preparation grade of the substrate. NOTE The data given in this document was obtained using the methodology described in Annex A.

ISO 8502-4:2017 gives guidance on the estimation of the probability of condensation on a surface to be painted. It may be used to establish whether conditions at the job site are suitable for painting or not.

ISO 8502-2:2017 describes a method for the determination of chloride-containing salts that are readily soluble in water and are present on a steel surface. The method is also applicable to previously coated surfaces. ISO 8502-2:2017 includes a method, applicable in the field or in the laboratory, for washing off the surface while several methods are referred to for chloride analyses.

ISO 8502-3:2017 describes a method for the assessment of dust remaining on cleaned steel surfaces prepared for painting. It provides pictorial ratings for the assessment of the average quantity of dust. It also provides descriptive classes for the assessment of the average size of the dust particles. The method described is a qualitative test useful for a steel surface, before cleaning, corresponding to rust grade A, B or C as defined in ISO 8501‑1. It can be used as a "pass/fail" test or to provide a permanent record of the dust present on a surface.

ISO 8501-1:2007 is a hardback A5-format book in four languages (English, French, German and Swedish), which specifies a series of rust grades and preparation grades of steel surfaces. The various grades are defined by written descriptions together with photographs that are representative examples within the tolerance for each grade as described in words. It is applicable to hot-rolled steel surfaces prepared for painting by methods such as blast-cleaning, hand and power tool cleaning and flame cleaning, although these methods rarely lead to comparable results. Essentially, these methods are intended for hot-rolled steel, but blast-cleaning methods, in particular, could also be used on cold-rolled steel of sufficient thickness to withstand any deformation caused by the impact of the abrasive or the effects of power tool cleaning. This part of ISO 8501 is applicable also to steel substrates that show residues of firmly adhering paint and other foreign matter in addition to residual mill scale.

ISO 8502-11:2006 describes a field method for the assessment of the surface density of water-soluble sulfate on steel surfaces before and/or after surface preparation.

ISO 8501-3:2006 describes preparation grades of welds, cut edges and other areas, on steel surfaces with imperfections. Such imperfections can become visible before and/or after an abrasive blast-cleaning process. The preparation grades given are to make steel surfaces with imperfections, including welded and fabricated surfaces, suitable for the application of paints and related products.

ISO 8502-6:2006 describes a method of extracting, for analysis, soluble contaminants from a surface by use of flexible cells in the form of adhesive patches which can be attached to any surface, regardless of its shape (flat or curved) and its orientation (facing in any direction, including downwards). The method described is suitable for use in the field to determine the presence of soluble contaminants before painting or a similar treatment. This part of ISO 8502 does not cover the subsequent analysis of the contaminants that have been dissolved off. Methods of analysis suitable for field use are described in other parts of ISO 8502.

ISO 8502-2:2005 describes a method for the determination of chloride-containing salts that are readily soluble in water and are present on a steel surface. The method is also applicable to previously coated surfaces. It will normally be used in a laboratory using washings sampled from surfaces on site. ISO 8502-2:2005 is applicable to the determination of salts that have been deposited on the steel surface before, during or after the cleaning operations. ISO 8502-2:2005 is not applicable to surfaces treated with chromate, nitrite or amine, which are commonly used as inhibitors in the water when wet blast-cleaning. This is because a chromate concentration of 10 mg/l or greater or a nitrite concentration of 20 mg/l or greater in the wash water interferes with the determination of the chloride. Also the amine inhibitors can form a hydroxide boundary layer (not water soluble) over the substrate and prevent the water from contacting the underlying salt for its removal. An iron(III) ion concentration of 10 mg/l also interferes with the determination, but the iron(III) ions are concentrated in the rust deposits, which are removed from the test solution by filtration.

ISO 8502:2003 describes a field method for the determination, by drop titration, of soluble ferrous ions on steel surfaces before and/or after surface preparation. The method is intended mainly for use in the assessment of contaminants on a surface. It is easy for unskilled personnel to carry out and it is sufficiently accurate for most practical purposes.

Describes a method of extraction, intended for analysis, of soluble contaminants from a surface by means of adhesive patches which can be attached to any surface, regardless of its shape and orientation. Suitable for use in the field before application of paints.

May be used to establish whether conditions at the job site are suitable for painting or not. The method specified is based on measuring air temperature and relative humidity, calculating the dew-point, measuring the steel surface temperature, and estimating the minimum surface temperature (above the dew-point) that is needed to avoid condensation under the prevailing environmental conditions. Annex A contains a table for determination of dew-point.

Provides pictorial ratings for the assessment of the average quantity of dust as well as descriptive classes for the assessment of the average size of the dust particles. The method is based on pressing a pressure-sensitive adhesive tape on to the steel surface to be tested. It may be carried out as a "pass/fail" test by comparison with specific limits or by permanently recording the dust present on a surface by mounting the tapes used on tiles, cards or paper.

Describes a method for assessment of chloride-containing salts that are readily soluble in water and are present on a steel surface or on a previously coated surface. The method cannot be used on surfaces treated with chromate or nitrite. An iron(III) ion concentration of 10 mg/l also interferes with the determination. Warning: The substances and procedures used in this method may be injurious to health.

Describes a test method which uses indicator test strips that are sensitive to ferrous ions in order to assess the soluble iron corrosion products on surfaces abrasively blast-cleaned. Does not apply to manually cleaned steel surfaces. Annex A is for information only.