Massive chunk of paint gone on the corner of the door with some corrosion.

[glazewolf]

!!!!!!!

[Renaissance_x]

By touch up paint do you mean the tin's of touch up paint?


If you mean from a paint tin yeah it should be fine so long as you rough it up and prime it.
Take not that the colkour more than likely won't match up properly though.

[white_ep3_civic]

If it's just a couple of little bits if paint missing I just used a fine brush and carefully painted it. You would never know they were there. No primer and only cost about $25 all up

[tony1234]

Post pics so we can best advise you on what to do.

[WarrenM]

I attached the images. The flash reflected off the primer and metal underneath but you can see the corrosion on the second picture.

I don't know about anyone else, but I can't see anything in the second photo. Can you photograph outside without a flash, a little further away?

If you want to do it properly, this is what you do:

1. Protect everything which you don't want to paint, using newspaper and masking tape. EVERYTHING which the paint can possibly reach!
2. If the rust is surface only, use a medium grit disk mounted on a drill to grind down to the bare metal, ensuring that no corrosion remains.
3. If the rust looks like it is through the metal, you can use a rust converting paint, but you may just be deferring and making worse the inevitable major rust cut-out and metal weld.
4. Fill the entire area with a good quality body filler, so it looks just like the matching panel on the other side, or if you aren't skilled in its use, make it higher than it should be and sand it back (see next step).
5. Allow the body filler to dry completely, then carefully sand the area with sandpaper which has been wrapped around a block of wood. When sanding, begin with a 36-grit sandpaper and work up to a 120-grit sandpaper.
6. Use a spray primer to prime the area, being sure to use a primer specially designed for automotive use. Six coats of primer should be used, allowing each coat of primer to dry completely before applying the next coat.
7. HINT: Every time you use a spray primer or paint, shake it for a minute, even if you used it two minutes before. Every time you finish spraying, turn the can upside down and spray until the nozzle clears, even if you plan to spray again in under a minute.
8. Sand the primer using a 600-grit wet and dry sandpaper (wet of course). This will help to remove any scratches.
9. The area should then be touched up with a matching automotive paint. Use at least three coats of light spray to start (Use 15 coats to start if you you are doing this on a Rolls Royce rather than a Honda). Use wet and dry sandpaper (wet) between coats.
10. If the paint is not smooth, resand and repaint the area until you have a smooth surface. Don't get frustrated and don't spray heavily. You will get to a point where you will KNOW that the paint is right.

Regards
Warren

[WarrenM]

I don't know about anyone else, but I can't see anything in the second photo. Can you photograph outside without a flash, a little further away?

If you want to do it properly, this is what you do:

1. Protect everything which you don't want to paint, using newspaper and masking tape. EVERYTHING which the paint can possibly reach!
2. If the rust is surface only, use a medium grit disk mounted on a drill to grind down to the bare metal, ensuring that no corrosion remains.
3. If the rust looks like it is through the metal, you can use a rust converting paint, but you may just be deferring and making worse the inevitable major rust cut-out and metal weld.
4. Fill the entire area with a good quality body filler, so it looks just like the matching panel on the other side, or if you aren't skilled in its use, make it higher than it should be and sand it back (see next step).
5. Allow the body filler to dry completely, then carefully sand the area with sandpaper which has been wrapped around a block of wood. When sanding, begin with a 36-grit sandpaper and work up to a 120-grit sandpaper.
6. Use a spray primer to prime the area, being sure to use a primer specially designed for automotive use. Six coats of primer should be used, allowing each coat of primer to dry completely before applying the next coat.
7. HINT: Every time you use a spray primer or paint, shake it for a minute, even if you used it two minutes before. Every time you finish spraying, turn the can upside down and spray until the nozzle clears, even if you plan to spray again in under a minute.
8. Sand the primer using a 600-grit wet and dry sandpaper (wet of course). This will help to remove any scratches.
9. The area should then be touched up with a matching automotive paint. Use at least three coats of light spray to start (Use 15 coats to start if you you are doing this on a Rolls Royce rather than a Honda). Use wet and dry sandpaper (wet) between coats.
10. If the paint is not smooth, resand and repaint the area until you have a smooth surface. Don't get frustrated and don't spray heavily. You will get to a point where you will KNOW that the paint is right.

Regards
Warren

Final words of warning.

• Don't paint final coats if the temperature is above 30 degrees in the shade - paint dries too fast for a good shine. The cooler the better (but of course you have to wait much longer between coats)
• Duco changes colour and tone over time. If you expect an absolutely perfect colour match on an old car, you are not going to be happy - go to a professional. You can still save yourself a lot of the cost by doing everything (properly) prior to the colour spray.

[WarrenM]

would having touch-up paint over the corrosion stop it or would it just corrode quicker after applying the touch-up paint?

Touch-up paint will not stop corrosion once it has taken hold but it may slow it down, depending on the availability of oxygen to continue the rusting process. Rust is its own catalyst so existing rust will accelerate the rust reaction if both iron and oxygen are available.

You need to treat the rust with a rust converter to stop the rust completely. With or without a rust converter, painting over the rust may reduce or remove the available oxygen which will slow or stop, at least temporarily, the rusting. Rust converters react with rust (iron oxide) to form (usually) iron tannate, which is very stable. So clearly, if the rust is replaced by iron tannate, the rust reaction will dramatically slow, and that makes the protective action of the primer or paint much easier.

It is not quite as straightforward as I have made out, but that is the essence of it.

Regards
Warren