sanded through color with polishing kit

[kurth]

Unfortunately, though not completely unexpectedly when polishing my Revell S&H torino I sanded through to the primer on the ridge which runs down the middle of the hood. I am surprised it was the only spot I sanded though, with all the ridges and creases in the body.

 

My question is, what is the best way to touch up the paint? do I need a whole coat on the hood? Can I just lay several coats down the middle on the ridge and blend it in?  

 

I used MM enamel and no clear coat.  I remember running into a similar issue years ago but I can not remember what I did to fix it.

[Snake45]

Sometimes you can touch up such a booboo with a brush. But the middle of the hood is a pretty prominent place, so you might have to just go ahead and shoot another coat of paint (or two).

[Fat Brian]

Are you using an airbrush or spray can? With an airbrush you can probably get a fine enough line to just paint the middle half inch of the hood with another color coat and be fine. If you're using a spray can painting the whole hood will be easier since masking it will leave a noticeable step to deal with. Just be sure to get all of the polishing compound off, especially if it is a polish/wax combo.

[mikemodeler]

I agree with Brian, especially the part about making sure the compound is completely off of the hood. There will be adhesion issues if there is any residue left from the polishing compound.

[Ace-Garageguy]

If you want a first-class undetectable repair, your best bet is really to shoot the whole hood. It's a small enough part, so why not?

Even if you airbrush, you run into the possible difficulty of polishing out the blend-edges where the new line of paint leaves a slightly dry-spray edge overlapping the old paint. Polishing this out can often result in going through the paint somewhere else and repeating the whole problem.

To get all the polish residue and any possible wax or silicone contaminants off (which can cause fish-eyes in your new paint) I'd recommend a thorough cleaning with 70% isopropyl alcohol. It shouldn't hurt fully cured enamel.

Then, to insure good adhesion, I'd recommend scrubbing the surface with an abrasive cleanser like Comet, hot water, and a toothbrush. Rinse VERY well.

There's also the potential problem of lifting and / or wrinkling you face when shooting enamel over enamel. You're fine as long as the old paint is COMPLETELY cured, but if it's still in the "recoat sensitivity" window, you can get a real mess. Even that's not a disaster though, as enamel strips easily.

[bobthehobbyguy]

If you put a couple of clear coats before polishing then you know you've gone through the clear when you start seeing color.

[Snake45]

If you want a first-class undetectable repair, your best bet is really to shoot the whole hood. It's a small enough part, so why not?

Even if you airbrush, you run into the possible difficulty of polishing out the blend-edges where the new line of paint leaves a slightly dry-spray edge overlapping the old paint. Polishing this out can often result in going through the paint somewhere else and repeating the whole problem.

To get all the polish residue and any possible wax or silicone contaminants off (which can cause fish-eyes in your new paint) I'd recommend a thorough cleaning with 70% isopropyl alcohol. It shouldn't hurt fully cured enamel.

Then, to insure good adhesion, I'd recommend scrubbing the surface with an abrasive cleanser like Comet, hot water, and a toothbrush. Rinse VERY well.

There's also the potential problem of lifting and / or wrinkling you face when shooting enamel over enamel. You're fine as long as the old paint is COMPLETELY cured, but if it's still in the "recoat sensitivity" window, you can get a real mess. Even that's not a disaster though, as enamel strips easily.

Yeah, might as well just strip it and repaint the whole thing. Not a huge deal for just a hood.

[kurth]

Thanks for your assistance.

I did use an airbrush. I did not use any compound on the hood  yet, just the sanding cloths.   A good wash with some blue dawn will ensure the sanding sludge is gone. 

 

 

 

 

[PeeBee]

I keep a supply of a full palette of Sharpies on hand for these instances.  As careful as I try to be, I often polish through high spots.  However, they're usually very small, narrow areas such as the top of a tail fin (never the whole length of the fin - I usually catch myself...), hood and fender creases, etc.  I find that if I very carefully run a Sharpie that's close to the color I've applied over the affected area, that usually does the trick.  This works best with solid primary colors and neutrals, but I've had success with metallic, complimentary and analogous colors as well.  Lighter colors (whites, yellows, beiges) can be tricky.

I try to be as accurate as possible and to perform the touch-up with just one shot.  If I have to hit it again, I make sure the first application has dried thoroughly.

When successful you'd be hard-pressed to detect the repair.  It doesn't work for every situation, though, and I've done my share of "dry-brush" touch-ups and re-sprays.

PB.

[Snake45]

I keep a supply of a full palette of Sharpies on hand for these instances.  As careful as I try to be, I often polish through high spots.  However, they're usually very small, narrow areas such as the top of a tail fin (never the whole length of the fin - I usually catch myself...), hood and fender creases, etc.  I find that if I very carefully run a Sharpie that's close to the color I've applied over the affected area, that usually does the trick.  This works best with solid primary colors and neutrals, but I've had success with metallic, complimentary and analogous colors as well.  Lighter colors (whites, yellows, beiges) can be tricky.

I try to be as accurate as possible and to perform the touch-up with just one shot.  If I have to hit it again, I make sure the first application has dried thoroughly.

When successful you'd be hard-pressed to detect the repair.  It doesn't work for every situation, though, and I've done my share of "dry-brush" touch-ups and re-sprays.

PB.

Great tip! I don't see it working every time, but I can definitely see it working in certain cases. And when it does work, it would save HOURS of time!

[Miatatom]

Thanks for your assistance.

I did use an airbrush. I did not use any compound on the hood  yet, just the sanding cloths.   A good wash with some blue dawn will ensure the sanding sludge is gone. 

I believe that the sanding cloths contain silicone. As Bill said, that will cause fisheyes. Follow his recommendation and WASH THOROUGHLY! I always use Dawn. Get the blue stuff with no moisturizers in it.

[StevenGuthmiller]

I think this entire thread is a perfect promotion for clear coats.

 

Steve