It should never be assumed that the correct coating materials for a project have been delivered to the work site or the paint shop.
·Ensure that the paints provided to the site or shops match with the requirements of the specification and that all paints to be used on a surface are supplied by one Paint manufacturer.
·Ensure that the paint is the correct type for the application method being used by the contractor.
·Record the batch number, and date of manufacture of the paints.
·Examine the storage conditions and make sure that they are in line with the requirements of the specification and the manufacturer’s product data sheets.
·Make sure that there are sufficient materials in storage for the completion of the contract or that there are sufficient materials earmarked for the contract in a central storage area.
·Be present to observe the subject of the coatings from the storage area at the start of the work period.
The success or failure of a paint coating is often determined before a drop has even been applied.
The apparently simple tasks of mixing and thinning are often found to be the root cause of many coating failures.
The primary goal of mixing paint is obviously to provide a homogeneous liquid. Serious problems result when this is not achieved.
Ensure that:
1) all coatings are thoroughly stirred by mechanical means with an electric or air powered stirrer so that there is no residue on the bottom of the container;
2) two-pack (multi-component) materials are handled as noted below.
Two-pack (multi-component) coating materials require special attention.
Two-component paint materials, such as most epoxies and urethanes, are normally supplied by the manufacturer in two containers of correct, pre-measured proportions. It is important when mixing that complete rather than partial kits are used to avoid creating the wrong volume of one component with relation to another.
Best results are generally achieved by mixing each component separately before they are mixed together, but once again, the application data sheet should be the first port of call before mixing.
It is often important that the two components be combined in a particular manner. The data sheet may detail whether Component A is to be added to B or vice versa. It is always advisable to add and mix the two components of a paint gradually to achieve an homogeneous mixture and to avoid areas of high and low concentrations.
1) Ensure that any induction time is strictly followed.
Some two-component materials, such as epoxies, require a specific induction or “sweat-in” time, generally about 15-30 minutes. This time allows the two components to start reacting chemically before the paint is applied.
2) Ensure that no material is used after the expiration of its pot life.
Pot life is the length of time after mixing during which two-component paints can be successfully applied. After too much time has passed, the paint reacts chemically to a point where it should no longer be used.
3) Thinning
Occasionally, it is necessary to decrease the viscosity of a paint by adding a thinner so it can be applied effectively. When the need for thinner arises, it is very important that you follow the manufacturer’s recommendations in the data sheet exactly.
Just enough thinner should be added to give the desired application viscosity. Over-thinning will produce a runny material and cause problems achieving the required film thickness.
·Ensure that any additions to the coatings are strictly in accordance with the manufacturer’s recommendations.
·Ensure that all necessary sampling procedures and testing have been carried out prior to the start of the work.
·Ensure that all necessary material sampling and testing procedures required by the specification during the course of the work are completed satisfactorily.
Paint Application
The durability of paint material depends on:
•the quality of its manufacture as well as
•surface cleanliness,
•uniformity of application, and
•conditions during application, curing, and service.
Inspect that the coating is applied only to surfaces suitably prepared to the specified standard of cleanliness.
1) Confirm that the environmental conditions are acceptable for the application of the coatings.
2) Confirm that the particular coating being applied does not have any special limitations on its application.
3) Confirm that the surface to which the coating is being applied is free from moisture, oil, grease, dust, grit , corrosion products, debris , or other contamination that would advesrsely affect its performance.
4) Confirm that the coating is applied within the minimum and maximum over-coating intervals.
·Confirm whether a stripe coat has been specified and applied correctly.
·Confirm that each coat of paint is uniformly applied and free from runs, sags, etc.
·Ensure that any areas of defective coating are marked for remedial attention and that the contractor’s supervisor is aware of the areas marked as well as the repairs required.
·Re-check areas previously marked as defective to ensure that remedial work has been done.
·Inspect predominantly the areas that are less accessible to ensure complete coverage of all surfaces.
·Pay particular attention to areas around edges, weld seams, cut-outs and scallops throughout, difficult corners on angle beams, areas where water might accumulate, and areas that are difficult to see without an inspection mirror.
·Measure the wet film thickness of the coating immediately after application to ensure that it is in accordance with the recommendations of the data sheet and that the dry film to be obtained will meet the requirements of the specification.
·Measure the dry film thickness to ensure that it meets the requirements of the specification.
·Ensure that the dry film thickness measurements are in agreement with the expected value calculated from the wet film thickness measurements.
In the event of a serious discrepancy between the dry film thickness measurement and the expected measurement based on the wet film thickness reading, the coating material should be checked in order to ensure that only authorised additions were made.
Complete any special tests (e.g., adhesion DIN EN ISO NF 6860 & DIN EN ISO NF 2409, cure ASTM D5402 & ASTM D4752 , salt ISO 8502-6 & ISO 8502-9 Bresle - salt contamination test by conductivity measurements , pinhole/ holiday ISO 2746 & BS EN ISO 829 A , etc.) that may be prerequisite by the specification.
·Confirm that the completed work is uniform in colour.
·Confirm that the equipment is adjusted and maintained as recommended by the equipment and material manufacturers
·Confirm that the handling of items during and after painting is carried out in such a way that the coatings are not damaged.
·Confirm that the handling of items are not moved before the coating is sufficiently hard to withstand handling damage.
·When damage does occur, ensure that remedial work is carried out properly and to the satisfaction of the specification requirements.