How to do three-layer paint repairs

Making efficient three-layer paint repairs

Three layer paint finishes, like Mazda 46V "Soul Red" and Ford M7283A "Ruby Red" are getting increasingly popular on cars today, and although they look great, making an exact colour matching can be quite difficult. Based on the new Mazda 46V “Soul Red” colour, we’ve made a guide for how to ensure exact colour matchings without the risk of time-consuming re-do’s.

As understanding the three-layer paint finish and sticking to a step-by-step process goes a long way towards making these repairs, you will find both a video and a thorough guide below.

Following correct processes and techniques and gaining a little experience will soon have technicians confidently producing a high quality repair. If you want to further improve your three-layer skillset, sign up for our Master Applicator III course, which offers a practical, hands-on training on the subject.

Step 1: Identification

The first crucial step is to determine whether the vehicle colour is actually a three-layer finish. These days, there are far more than just the traditional white three-layer finishes. Many mainstream vehicles now have three-layer colours in red, blue, orange, yellow, etc. even though they may not initially appear to be one of these more complex paint finish. Identification should happen at the quoting stage to allow the necessary labour time to be included and to avoid costly delays later in the repair process. Extra colour matching time is generally needed and, in the paint shop, extra booth time is required to apply the extra number of coats. Often, doing three-layer finishes is best left to be done as the last job of the day, when the booth is generally available for longer. It’s vital to allow extra room for blending – generally one full panel – and remember both ground-coat and mid-coat need blending.   Simultaneously, ensure the painter has the necessary skills and time to efficiently do the job. Especially if it’s a new colour, it can be well worth a quick call to your Nexa Autocolor Technician for guidance – it’s far more efficient than waiting until a redo is required!

Step 2: Colour Matching

Since differences in application techniques can significantly influence colour accuracy for three-layer finishes, it’s best to have the colour matched by the employee who will actually apply it. Gun settings and application techniques (such as distance from panel, travel speed and overlap) must be consistent between the colour matching stage and painting the vehicle. Note: With so many variables affecting the colour match and application, Nexa Autocolor does not recommend edge-to-edge colour matching.

 

Step 3: The three-layer colour spray-out process

With three-layer finishes the mid-coat greatly influences the colour accuracy. As more coats are applied the colour varies – darker or lighter (generally darker), tonally and in the effect level. Therefore, producing a few spray-out cards is absolutely essential. The following procedure is designed to avoid the common issue where applying the wrong amount of base- or midcoat changes the colour of the repair unintentionally.

Set up 5 spray cards in the correct spectral grey primer nuance. Apply equal basecoat on all cards – dry completely. Note: Ensure the same shade of spectral grey primer is used on the actual repair.

• Apply basecoat to all five cards. Allow to dry. Remove one of them.
• Apply the first layer of midcoat to the remaining four cards. Allow to dry. Remove one.
• Apply a second layer of midcoat to the three remaining cards. Allow to dry. Remove one.
• Apply a third layer of midcoat to the two remaining cards. Allow to dry. Remove one.
• Apply a fourth layer of midcoat to the last card. Allow to dry.Apply equal clearcoat to all five cards. Allow to dry.
• Using a Sun Gun, check the four cards against the vehicle to determine the number of mid-coats required.
• During mid-coat application in the booth, use the side of the spray-out card (with a Sun Gun) to check the number of mid-coats is correct. Once confirmed, clearcoat can be applied.
• File the spray-out card in your ‘painter’s library’.

Step 4: Application

An even application is essential because mid-coat film build can dramatically affect the end result. For example, ‘double overlaps’ at the end of gun strokes leads to areas of big colour difference, especially if duplicated over three or more mid-coat applications. Staggering start-stop positions reduces the likelihood of ‘zebra stripes’ appearing, especially when coating the entire side of the car.

Note: Both the ground-coat and mid-coat should be applied as normal, closed coats. Also remember to rectify any defects or inclusions in the ground-coat before mid-coat application because they’re often visible through the transparent layer.

Step 5: Blending – ground-coat

The secret is in precise and progressive blending of both the ground-coat and mid-coat within a specified area. Also, if applying Wet-on-Wet primer, it should be bended into the adjoining panels as well. If three mid-coats are required to achieve a colour match, the basecoat will need to be blended in three stages. Mentally divide the blend panel into five or six equal sections and blend the ground-coat within the first section. Use reverse blending techniques to contain overspray and prevent droplets being pushed to the panel end. 

Performed correctly, this process produces a very soft, progressive transition of the ground-coat into the existing colour which is the key to success when blending three-layer finishes.

Step 6: Blending – mid-coat

Blending the mid-coat is far simpler, since conventional blending techniques can be used, however precision is still important.

The first coat is taken to the end of the first section of blended basecoat, the second coat to the end of the second section and the third to the end of the third section. Be sure to tack-rag the back of the blend area in between all coats in order to remove over-spray and avoid ‘profiling’ after the clearcoat is applied. Take care to avoid excessively increasing mid-coat film build as this is the main cause of darkening of the blend edge. High ground-coat film-builds often occur during three-layer applications so it’s important to allow extra flash off time prior to applying the specified Nexa Autocolor clearcoat to prevent solvent entrapment from causing durability issues.

Training

If you’ve never worked on three-layer paint repairs before, the procedures in this article can seem complex. It’s recommended that do a test and build up your skills and experience before attempting a ‘live’ job in the workshop – it’s much more cost effective and less stressful than waiting until a mistake leads to a redo. Getting expert guidance and gaining some hands-on experience of the three-layer repair process is as simple as contacting your local Nexa Autocolor Technician. Nexa also regularly conducts courses on three-layer repairs as part of the Master Applicator III course at our Nordic Training Center in Copenhagen.

See our course catalogue here