Why do people say it is difficult to touch up conversion varnish? In most cases, lacquer touchups adhere well enough. It's easier to do burn-ins on CV because the hot knife doesn't mar the finish as readily as it will mar a lacquer finish. It seems to me that CV is at least as easy to touch up as lacquer. Furthermore, when a job is finished with CV it doesn't get damaged as easily as a lacquer finish, thereby reducing the number of necessary repairs. If you're dealing with major damage, you have to recoat the entire area, whether it's lacquer or CV. Why not just use CV?
I agree. Beats me as to why other people think this is an issue.
As the effect of the damage goes further down into the substrate, the repairs get more difficult, the transparent finishes being the hardest of the repairs.
Yes, when you can re-coat the whole surface after the repair is made with compatible and equal material, you have a good repair. When a lacquer or even a pre-cat is used in the repairs, it changes the whole integrity of the repair and the finish, and then it becomes a cosmetic repair.
The ultimate repairs are where no coating is used, only a clear filler and at times some color added, and then sanding/polishing pads are used to level and polish up the filler, and then compounding is done to complete the repairs. These are the most difficult repairs of all.
Being able to do the repairs in your shop where you have time is the way to go, but when you go out into the homes and offices where you cannot spray, I don't think you can call any of these catalyzed repairs a piece of cake.
Has anyone used an air brush? Will it work on CV? I have thought about trying one for small touchups.
First you need to evaluate the defects. Are all the edges smooth or ragged; is the bottom of the defect also smooth? If not, sand them all to a polished edge. Blow off any dust, and prepare to do your filling.
I find if I severely limit my repair to just around the scratch and carefully fill/sand/color just that area, I do better on the repairs. It's when I get aggressive and sand too far out into surrounding areas that I compound my problems.
I do high-end entry door repairs and these cross-grain scratches combined with a level finish and 40 sheen or higher are incredibly difficult for me. Fortunately I have a high hourly rate that begins when I leave the shop!
I try to avoid rubbing out any scratches in conversion varnish and frankly, most damages are not scratches that can be rubbed out. The catalyzed conversion varnish does not scratch easily (as noted in the previous discussions).
I find most touchups to be easiest using a set of touchup markers for color. Each can be used individually or mixed to match the desired color in a puddle of topcoat, conversion varnish, and applied with a fine artist's brush or the edge of a small piece of paper.
Deeper gouges and scratches should be filled with a putty stick, especially those out of the way places and nail holes, but larger and more obvious gouges and scratches should be filled with a burn-in stick.
For severe damage a total refinish of the surface may be necessary, either in the shop or on site. Most of the time a refinish can be done on site if the damaged area can be sanded to breaking lines in the piece, such as the whole edge of a door, or the face of a raised panel. Small Preval spray cartridges can be used on site to spray conversion varnish. They work great.
Any other problem, bring larger equipment or get it back to the shop.
There is nothing written in stone about how to do every type of repair. Options, alternatives and adjustments are a very important part of completing your repairs.
I will pass on one more technique on doing repairs that was not mentioned. If the damages are in the clear coat, polish off the edges in the clear coat, and if the damage is down into the substrate, here is what you must do to get good repairs:
1) There must not be any ragged edges. Use a razor blade to cut the damage into an oval shape.
2) Sand and polish the entire damage, including the edges.
3) Fill the defect only up to the wood line, and on your clear finishes use a gold base color for reflectivity, then add in any stain/toner colors and any grain lines.
4) Sand the coating in an inconspicuous spot and look at the sanding powder to see the color of the coating (water clear, amber).
5) Apply the same type of coating, then adjust the sheen.
This is a condensed version - add in the options for your types of repairs.
An addendum: Whenever you're repairing damages that are down into the substrate in any of the solid opaque colored finishes, you will find many of these finishes are first color coated and then clear coated. You must follow this same process when you're doing the repairs.
It is very important to fill only up to the wood line (to the color coats). You must allow some space for your clear filler. Otherwise you will never get a good color match in the repairs.
You also must be sure to check if the topcoats were amber or water clear. As I mentioned, test for this sand in an inconspicuous spot and check the sanded powder for color. It will tell you what the final coat was. It may be the same color or it may be an amber or water clear coat.
Finish off your repairs the same as was originally done.
Comment from contributor O:
I agree that doing a touchup is not a piece of cake. Touching up is a skill which is a part of a top-notch finisher's job. Finishers with a background in art have an eye for colors and are very sensitive to details. Touching up is like restoration of an antique painting. This is what I normally do with a cross grain scratch.
1) Lightly sand the topcoat of the item.
Usually finishers use the same toner to touch up the scratch, but most often it will not match, especially on a cross grain scratch.
If they choose to keep the piece on site, I write in my work order that the client understands and accepts that traces of the original damage may remain visible, and have them sign it. So far (28 years) I've had only one complaint after signing, by a difficult and unreasonable client.