Facts & Fiction Regarding Repairing & Buffing Topcoats
Fender rub, difficult moorings and general wear & tear all mean that topcoat repair and maintenance in-service is a fact of life. So what do you really need to know?
Captains and crew are increasingly getting involved in the choice of paint, and 'repairability' is increasingly sought after, but there are pitfalls which you can and should avoid.
Topcoats offered for yachts can be simply divided into two types on the basis of their fundamental resin chemistry: Polyester Urethanes such as the classic Awlgrip®
Acrylic Urethanes (Acrylics) such as Awlcraft® 2000
So what is the difference between the AwlGrip and AwlCraft resins?
Well, it seems that size does matter- molecular size.
Polyester Urethane molecules are much smaller than Acrylic molecules. So when they cure the Polyester urethane forms a tighter matrix which gives a harder, more abrasion resistant film, with better chemical resistance than the Acrylic.
Acrylics though, do have key advantages of their own. They are more forgiving in application, trap less dust and are therefore buffable (but more on that later). So there are good reasons to choose each. Both Awlgrip and Awlcraft 2000 will resist staining and provide long lasting gloss.
How they work
One of the reasons these paints last as long as they do is because they stratify in to a resin rich layer at the surface and a pigment rich layer underneath. The outer layer provides long term protection for the pigment particles, which improves color and gloss retention and provides the deep gloss associated with high quality urethanes. Any buffing will remove film thickness, which in turn may reduce longevity and may affect manufacturers' warranty.
Buffing your topcoat be it part of a repair, touch-up, polishing or maintenance schedule
So what happens when you buff the paint? It depends on the resin type, acrylic or polyester. While it is true that EVERY topcoat may be buffed, not every topcoat will be unaffected by the process.
The diagrams below show how chemistry and buffing affect the performance of the coating.
Undamaged, the resin rich outer layer provides protection from weathering.
Here we see a simulated damaged area that needs buffing out. This could be something like a scratch for example.
This diagram shows what happens when you buff a polyester urethane. Because the paint is a very hard rigid film to get rid of the scratch you need to cut deeply into the paint, leading to exposure of the pigments. This looks shiny to begin with but the long-term performance of the finish is now compromised. Regular applications of the Awlcare Protective Polymer Sealer will be necessary to maintain the finish.
Very light polishing of a Polyester Urethane may not lead to this problem but this is rarely enough to remove scratches and certainly not enough to blend in areas that have been touched up with fresh paint.
When an acrylic urethane is buffed, due to the lower cross-link density the melting point of the resin is much lower i.e. it is softer. When buffing is carried out the resin-rich layer "melt" and reflow into the scratch. It is possible to retain an in-tact resin-rich layer at the surface protecting the pigments and not losing significant thickness. The edges of touch ups can be blended carefully in the same way. Long term performance is not affected as much of the resin layer remains. Use of Awlcare will protect this resin layer and further extend the life of the finish.
|Basic buffing and polishing guidelines|
|Below are some simple tips from buffing systems manufacturers:|
|Clean the surface with Awlwash prior to startingAllow the surface to dryApply a fine grade of polishing compound evenlyUse a clean buffing pad
Place the pad on the surface prior to startingBuff according to manufacturer's proceduresStart at a slow buffing speed
||Cut excessively into the paint layerPush down hard on the buffing machineUse excessive speed with the buffing padBuff in direct sunlight or if the surface is hotAllow the compound to dry on the surface|
Go Beyond the Factory-Looking Shine
So, you've chosen your Awlgrip finish, how do you protect it and keep it looking perfect day after day?
Awlgrip only recommends Awlwash and Awlcare for cleaning and protecting your finish
Awlgrip has proven that the use of Awlwash and Awlcare will extend the life of the topcoat with regards to gloss and color retention.
Awlwash Wash Down Concentrate- 73234
An effective detergent for cleaning, yet still gentle enough for frequent use on Awlgrip and Awlcraft 2000.
Awlwash has been extensively tested in Awlgrip's laboratories and in the harsh yacht environment.
Awlwash does not contain alkalies, acids or abrasives and is free rinsing, which decreases drying time
Awlwash is biodegradable and comes in a refillable quart, "Tip 'N' Measure" container, which makes it easy to get the proper mix ratio: One ounce of Awlwash per gallon of fresh water
Awlcare Protective Polymer Sealer- 73240
Awlcare will help temporarily seal and restore shine to painted surfaces that have become porous due to age or mistreatment. Once a painted surface becomes porous it allows dirt to collect on the surface making the normal washing process more difficult. Regular applications of Awlcare will help seal the porosity, helping to maintain a satisfactory appearance until there is time to repaint.
Awlcare contains no harsh abrasives and will not scratch the painted surface
Awlcare leaves a non-yellowing, protective polymer coating which lasts through multiple washings
Awlcare removes mild stains such as water spots and siesel soot and, with regular applications, increases resistance to attack from acid rain and other environmental pollutants