While I was sanding out the clear coat on the fairing, I sanded through in several places on flat surfaces; the front under the windscreen, on one panel on the side and several spots inside the headlight shell. 🙁 The clear coat was thin and went on too rough due to poor atomization.
NOTE: I fixed the problem causing poor atomization. It was caused by the air line fittings having small internal diameters. I bought some Devilbliss High Flow fittings. You can see the difference in the write-up on how I painted the parts in “LESSONS LEARNED: Replace Fittings with High Flow Fittings“. I installed the High Flow fittings before I shot the clear coat for the repair. As you will see later, the clear coat went on like glass. 🙂
Why You Can’t Blend Clear Coat Into Existing Clear Coat
Unlike the old days with lacquer, where you could blend in a patch since the solvents would melt the old paint and integrate the new paint with the old (it’s thermoplastic paint) you can’t really apply new clear coat on top of old and blend it in. It cures via a chemical reaction (it’s thermosetting) so the new clear coat can not blend in, but only sit on top adhering through a mechnical bond via the sanding scratches in the old clear coat. Therefore, there will be an edge where the new clear coat is very thin and this will eventually start to delaminate and peel.
Okay, so the correct solution is to sand the entire fairing with 1000 grit to rough it up and then respray it again with clear coat. But, I learned you can make a repair using the natural body lines of a part to limit how much of the part you have to spray with clear coat. As I have limited clear coat left, I’m going to try this to repair my mistake. But, this repair will eventually fail and the entire part will need to be clear coated again.
Here is where the sand through areas are. They are in very visible areas. I took these pictures after I had masked the parts.
“How To Do It” YouTube Videos
On YouTube, I found some helpful videos about repairing clear coat to avoid recoating an entire part.
- Eastwood: Basecoat Paint Repair on Kevins Korner with Kevin Tetz at Eastwood
- Eastwood: How To Repair Clearcoat – Kevin Tetz Shows the Best Way To Fix Paint-Part 1
- Eastwood: How To Repair Clearcoat – Kevin Tetz Shows the Best Way To Fix-Part 2
- Eastwood: How To Repair Clearcoat – Kevin Tetz Shows the Best Way To Fix Paint-Part 3
- How to Blend Clear Coat (Base / Clear) – Spot Repair
- How to Blend Clear by Back-Masking
Based on what I learned, this is the procedure I use.
- Sand the areas to be recoated lightly with 1000 wet paper to roughen it.
- Mask off the rest of the part to protect from overspray leaving a small gap next to the sections being repaired.
- Back tape along a trim line and over the tape used to mask the rest of the part.
- Set the gun for small fan and light coat.
- 1st base coat is away from the edge and light. Blend a bit toward the back taped edge.
- Peel tape back a bit.
- 2nd base coat should cover and be a bit larger area that 1st coat.
- Peel tape back a bit.
- 1st clear coat is light, tack coat. Keep very light at trim line.
- 2nd clear coat for coverage and gloss and covers entire panel.
- Peal tape off trim line and then lightly spray blender at the trim line edge to reduce height of clear coat edge.
- If blend line is rough, use 2000 grit to smooth out the transition between the new clear and existing.
- Buff at low speed on the blend to avoid removing the thin clear coat. Coarse buff then fine buff as on original clear coat.
The sand through areas on along the front of the fairing under the windscreen, on a small side panel and on the inside of the head light well. I mask off two different repair areas on the fairing using a technique called back taping.
Back taping forms the masking tape into a curve folded back on itself which you can see in the pictures above. When the paint hits the tape, it bounces back toward the repair area creating a gradual reduction in the amount of clear coat that tapers off as it gets closer to the tape. The edge is thin and can be blended into the existing clear coat without being visible.
I used painter’s plastic to wrap the sections of the fairing I am not working on to protect them for any clear coat overspray.
To prevent potential peeling of the soft clear coat, I “whet” the tape before applying it. I stick the small pieces to my jeans a few times and burnish the longer pieces across my pant leg to remove some adhesive and to reduce it’s stickiness.
Here are the masked off areas ready to shoot the clear coat.
I masked the side panel mto take advantage of hard edges and body breaks to help hide the edge of the new clear coat. I masked this section two times before I got what I thought was good back taping. It’s harder to do with curved body breaks.
Repainting the Base Coat
In some places I had sanded throught the base coat and of course it got scuffed when I sanded through the clear coat. I need to reapply more base coat so it will look like the original base coat. The Kevin Tetz videos show how to adjust an HVLP spray gun to get a small pattern and light paint application. But I decided to try out my new airbrush and use it for applying the base coat.
I use some of the left over Monza Blue paint that is mixed 2:1 with reducer that I saved just in case I screwed up and needed to patch the paint. I bought some eye droppers from Hobby Lobby so it is easy to fill the paint cup. I bought a hose that has a 1/4 inch coupling on one end and a Shrader (bycycle tire fitting) on the other that screws into the bottom of the airbrush. I added a quick connect fitting to the 1/4 inch coupling so I can snap the airbrush hose into the air line I use for painting.
I put a couple of eye dropper full amounts of paint into the airbrush cup. I don’t have a holder for the airbrush, but the spray gun holder worked okay as long as I put the airbrush in a slot near its balance point. I need an airbrush holder if I do air brush work.
I have not used an airbrush before. The one I bought is dual acting. I push down on the button to behind the paint cup to get air flowing and toggle it back to add paint to the air flow. The airbrush has a screw at the back that limits how far back I can move the button to reduce the amount of paint. I shoot some tests on a small piece of white note paper. I got some splats at first until I adjusted the screw in the back to get a light coat of paint.
I was concerned about putting too much paint on the sand through areas and it was hard to see how where the paint was going and how much was being applied. I took a small piece of white paper and put that in front of the sand through area. Then I sprayed on the paper to align the airbrush and adjust the spray so it was light and then removed the paper to put the paint on the spot I wanted it. I made small sweeps over the sand through sections to blend the edges. I sprayed 3 or 4 light coats until the new paint looked like the existing paint. This is the side panel and head light shell after touching up the paint.
After I finish touching up the base coat, I clean the air brush. It has very tiny parts and the needle is very sharp and thin. Be careful when you take it apart and reassemble it as it’s very easy to damage the needle. And small parts instinctively fall into the darkest, hardest to reach places under the work bench, DAMHIK 🙂
Spraying the Clear Coat
I hadn’t taken down the paint booth. I figured I’d end up fixing a mistake (how well I know myself 🙂 ).
I used my detail gun and mixed a small amount of clear coat. When I adjusted the gun I could hear and see the difference the new High Flow fittings made; the atomization was much improved.
I sprayed a light first coat and kept it away from the back taped edges. I let it flash for 10 minutes by the clock. The second coat I sprayed medium wet on the entire masked sections getting as smooth a surface as I could.
As soon as I finished spraying the 2nd coat, I sprayed some blender to help thin the edge of the new clear coat so it will not be as visible on the the old.
I sprayed it very lightly, or so I thought, but I got some sags. I sprayed a second light coat but one quick light coat is all it takes. Live and Learn. No worries as I’ve gotten good at sanding out sags and runs on this paint job.
Drying the Clear Coat
Kent Holt mentioned he has used halogen shop lights to bake his paint. I have two 500 watt lights on a light bar and decided to see much they would heat the repaired areas. I measured the surface temperature with my infrared thermometer. I could get 140 F or more with the lights about a foot away from the part. I baked each repaired section for 15-20 mins.
Here is the nose of the fairing where I had back taped it. The new clear coat is shiny and the rest of the fairing is dull as it’s wet sanded with 2500 grit.
Below, you can see below well the clear coat went on with the new High Flow fittings. It is very close to glass smooth with very minor orange peel.
For comparison, this is the result I got with the stock air line fittings. You can see how wavy the surface is and how coarse the orange peel.
Sanding and Buffing
I sanded the blender sags with wet 1500 grit until they were smooth. I lightly sanded the minor orange peel and sags with 2000 and then 2500 wet grit. On the edge of the new clear coat, I very lightly sanded with 2500 wet paper until I couldn’t feel any roughness or an edge.
I buffed out the repaired sections using Griot’s polish. I used the “2” setting on the 3 inch random orbital polisher so I wouldn’t take very much clear coat off near the blended areas.
Here is the fairing after buffing and polishing and painting the pinstripes on it. It is looking nice. It is not perfect, but it will work for awhile.