When planning a repaint project, it’s crucial to thoroughly assess the condition of the existing coating and substrate. This evaluation not only involves identifying surface defects but also understanding their severity to determine the necessary surface preparation and priming. By following a systematic approach, including the use of MPI’s Degree of Substrate Degradation (DSD) system, professionals can accurately forecast the required labor and materials, ensuring a successful outcome for any repaint project.
When planning a repaint project, assessing the condition of the existing coating and substrate is the first and most important step to ensuring a successful repaint project. This is because the state of the existing coating will usually dictate the type and amount of surface preparation and priming required. Evaluating the condition of the existing coating should not be confused with simply identifying the types of surface defects and failures present. Although recognizing the types of defects and failures is an important aspect of the evaluation stage, it is really only a portion of the assessment process.
To understand the whole scope of the project at hand, and to be better equipped to forecast the extent of labor and materials required; the severity of surface failure and defects on the existing coating must be determined. Below are 3 steps that are crucial to the success of planning any repaint project:
The Degree of Substrate Degradation (DSD) is a system that was developed to simplify the last step of the process listed above. The DSD system categorizes all existing surface conditions into 5 DSD levels with a DSD – 0 being an essentially ideal surface for repainting and a DSD – 4 being a surface that is badly damaged and requires structural repair. A more detailed explanation of the DSD system is described below:
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DSD – 0 |
This is an essentially “sound” surface. It may have visual defects, but the film is still protective. It may simply need a color, sheen, or other change. |
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DSD – 1 |
This is a “slight” degree of surface degradation. It is unlikely that the topcoat has been anything but insignificantly breached, and in no case is the substrate exposed. Surface preparation requirements should be “slight’ and only “touch up” with the top or intermediate coat should, in most cases, be necessary. |
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DSD – 2 |
This is a “moderate” degree of surface degradation. Damage to the film integrity is such that “spot priming” should, in most cases, be adequate after moderate surface preparation requirements. |
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DSD – 3 |
This is a “severe” degree of surface degradation. Damage to the coating is widespread. Necessary surface preparation will likely be substantial, and a full coat of the appropriate primer is to be expected. |
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DSD – 4 |
This is an essentially “unsound” surface. Repainting of this surface is unwise (except in cases where a temporary cosmetic remedy is deemed acceptable under the circumstances) as the substrate needs repair (i.e. beyond standard painting surface preparation), or replacement, before the appropriate coating system. |
Using the DSD system with the example posed above in Step 3, if the blistering is slight and there is a moderate amount of paint peeling down to the bare substrate, then the project would be a DSD – 2 and would require the surface to be cleaned with troubled areas spot primed. If the blistering and peeling is severe, then the existing coating must be removed entirely and the whole surface would need to be primed and then topcoated.
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Moderate to Severe |
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Oils/Grease |
Any |
Any |
Any |
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Rust Stains |
Slight (surface) |
Slight to Moderate |
Moderate to Severe |
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Sagging |
Slight to Moderate |
Slight to Moderate |
Moderate to Severe |
*Flaking/Peeling (1) – Flaking or peeling between topcoat(s) and intermediate or primer. Primer remains intact on surface
*Flaking/Peeling (2) – Flaking or peeling down to substrate. Primer removed from the surface.
Assessing the condition of an existing surface is necessary to the success of any repaint project, yet often this process ends once the types of defects and failures are identified and the next process of specifying systems begins. Planning a repaint project in this manner is not a good practice as the specifier is essentially basing their selection of a paint system off of an incomplete evaluation of the existing surface’s condition.
Consider a doctor that determines a patient’s arm is broken. The doctor still cannot properly recommend treatment for the patient until the severity of the break is established. Depending on the extent of the injury, the patient may require surgery and a cast for several months if the arm is severely broken, or may just need to rest for a few weeks if the break is just a hairline fracture. If the severity of the injury is not established, the treatment prescribed by the doctor is essentially a guess and runs the risk of over/under treating the issue at hand. Likewise for someone writing the specifications for a repaint job, they cannot specify the amount or type of preparation required for a repaint project until they can adequately assess the type and severity of defects afflicting the existing coating.