Blending clearcoat repairs

  • Thread starter Immortal Concepts
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Immortal Concepts

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Alright, so I have been asked a question about how to blend clear coat and avoid the dreaded halo. Right off the bat I will have to mention, for anything that has been uv damaged or spends a lot of time out in the sun, using this method is only a band-aid, you will maybe get 5 years if you are lucky, then it will form a white ring around the blend. You can thank oxidation for that. While this is still practiced in the professional world, its usually used for cheap customers and has a low supplies cost.

Now where this becomes practical in the airbrush world, is when a piece has been screwed up by a ding or a scratch, you usually go straight to a re-paint. This isn't true, many jobs can be saved at a fraction of the cost and frustration, if you have your colors mix cataloged for the job, and if you know how to blend clear properly. This can save you hours of having to redo a mural when you can just fix a small area of it. There is nothing worse than having to see something you spent 100s of hours painting, be sanded off. That is the one thing I hate about the pull trucks I paint, they blow up and no saving that!

Now you can skip this first step, but staying with my insurance claim requirements when doing this type of work, the whole panel will need to be polished. This will create a base for minimizing over-spray since the clear won't stick to polish.

After this, you will need to sand the area that has been damaged or nicked with 600 grit. The next step is to extend that area out with 1200-2500 grit. this will create a slope on the surface so that the new clear can bind into the old and level out. Anything over 1000 grit is polishing and the clear will not stick to it, so this ensures a nice level off when you cut and buff at the end. Keeping this in mind, when you spray your overlap, you don't want to come too far into it, or it will break the line when you buff it.

Now its time to blend your clear. No special clear is needed, any will do. I prefer to use the same system always, so that everything is always compatible, but isn't a requirement. Just knocks out any unknown variables.

The key to a good blend is as follows. You will want to spray quick and with a swooping twist motion. By this I mean snapping your wrist at the end and flaring up and away from the surface. Kind of like a dagger stroke, without the flooding. You want to make sure your fan is spraying all the way out and atomizing correctly. If you have your fan pattern too narrow, it will pool and run on you every time.
Now when you are spraying, spray into the repair. You want to minimize the over-spray so always point your gun towards the sanded area and not the edges. You will have to look at it with a light (I always used a sun gun) and you should be able to see where the edge is and how the clear is leveling out. If you see any small recesses in the clear, you can build up more in that area. Try to get it level as possible without getting any drips. Key is quick hand movements.

Now for the actual real trick for a perfect blend. Now they do sell what is called a blending solvent, but you can use the same reducer you used in your clear instead. While the clear is still fresh, spray reducer along the edge of the blend. On your 2nd coat of clear, spray about an inch or 2 past the first coat, then blend the clear edge again with the reducer. Make sure you stay within the area sanded with 600 grit. Like I mentioned earlier, anything over 1000 grit is polish, so the clear won't stick to it. The reducer levels out the edge and blends the new with the old. Since the surrounding edge has been sanded, the reducer reacts with the old clear and forms a chemical bond between the two. CAUTION: be sure when spraying the blending solvent or reducer, that you mist it on there, you don't want to flood it at all. I will just pull the trigger enough that it is atomizing and spray it on without opening it up full throttle. This offers better control and prevents runs and sags. Solvent will carry the blend out with very little needed, so don't over do it.

Now all you have to do is wait and make sure the clear is cured. Don't rush this step. If it's not ready then wait. If its not fully cured, the edge will break with the buffer. Sand the clear and blend with 2000 or 2500 then cut and polish. If you did everything correctly then the clear blend should be invisible.
 
Great write up, somehow I totally understood all of it, nice!
I agree ,I also understood everything you said Immortal, now if we could get the admins to make this a sticky in the tutorials that would be AWESOME
 
Nice write up my brother, never heard of the polishing tip but I will definitely bookmark this!
 
I had a Honda tank come back with a nick across the flames. I was told over and over ,it could not be repaired, so I repainted. Wish I had this 10 years ago, thanks Immortal Concepts
 
It's actually an old trick. Back from the lacquer days. I learned it in the 90s. Still holds true. Do remember though, I said if it's seeing daily sun, the blend only lasts up to 5 years before it turns white.
 
Nice write up Justin. You explain everything so clearly, even someone who has never cleared before will be able to understand it. :)
 
Just read this article. I use to do automotive paint touch up for used car lots and used this technique a lot and is hard to preform if inexperienced. Sanding out well past the repair is key for the blend. Like immortal said this is a repair and won't last forever so I would only use this technique on large panels if my customer was aware of the drawbacks. If it is a small panel or tank i would reclear the whole thing. I would never use this mid panel on a hood or top if at all possible because of the high visibility.
Not only can it fog after time, if the customer polishes often they can still break the blend after it is cured if they use a heavy cut polish and will leave an aroedesent ring around the repair. Best to reclear the panel or reserve the blend for a riser or smallest part of the panel. Something else should be mentioned here too, is matching the orangepeel of the old clear is a high value skill as well. Reducing the clear just right and setting psi and distancing to match the orangepeel takes practice. Do it in layers and let the layer flash off some between for a good bond. It is very easy to get sags in the blend because it is overreduced. Take your time with the blend. This is a good technique if applied correctly. Thanx immortal for the well written article.
 
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