Stripping your old finish
If you are stripping your old finish, get ready for a little work. These finishes are typically very thick and heavy. I myself, have lost a noticeable weight on a guitar taking these off, First, after you disassemble your guitar, have it ready in a work environment. Not the kitchen table. This is messy and smells so wear any PPE you need. Slowly use a heat gun to peel any polyester or polyurethane finish, A heat gun will also remove an older nitrocellulose finish. Check YouTube for these type of tutorials should you doubt yourself. Chemical strippers work, but they are very messy, more expensive, and worse for your skin. Use whatever method you are most comfortable with. As you slowly heat the finish it will peel. Use a drywall knife, scraper, or blade carefully to remove loose pieces (DO NOT gouge the body). Once the finish is gone you can assess the guitar body. You would be surprised what you can find under these thick cheaper Fender and Gibson/ Epiphone finishes. Don't worry, it's all repairable. It just takes a little time. Urethane finishes are more work typically. It is acceptable to sand these and use as a base for your Nitro finish, but if you are wanting a true vintage finish you will be going down to bare wood.
Ready for some sanding? Sand all of the imperfections in the guitar body with 220 -320 sandpaper. Remember to not leave any sharp corners in the pick up routs or control cavities. Take your time and always sand with the grain. Make sure your work is clean at the end. Some people will also first wipe the body down with naptha (camp fuel) or even water (a damp cloth, not wet). This will raise the grain and when you sand it will provide a flatter, smoother finish.
Now is the time to stain your guitar if you are choosing this method. Any scratches will be visible now. Make sure your sanding was perfect. Unless using porous wood. You will need to fill this.
Porous Woods (Ash, Walnut, Mahogany, Rosewood, Etc.)
Make sure you know if your wood is open grain or closed grain. For open grain, true professionals suggest a "wash coat". A wash coat is just a very thin coat of lacquer. Professionals used thinned lacquer. If you are using aerosols, just apply 1-2 very thin coats before the grain filling process.
Non Porous Woods (Maple, Spruce, Alder, Etc.)
You can proceed right to the sealer part of finishing.
This is a step used for more porous woods (Mahogany, Ash, Korina, Rosewood, etc). Make sure you know if your wood is porous or not. You can usually tell just from running your finger nail along it. If it feels rough it is because your nail is following the grain pattern. Most open grain woods are easy to spot. I have always used timbermate but there are oil based fillers available. It is very easy to use. It is water based and dries quickly. It doesn't shrink, sands easy, and they sell it already colour matched to your wood type. Although you can dye it to match anything. This has no shelf life and can be reconstituted to be used again and again by saving what you sand. it needs to be mixed into a slurry and brushed on (YouTube has many videos showing step by step what to do). Brush on with the grain and then against the grain. Make sure all the pours have filler in them and then before it dries, scrape the excess off the guitar to save time sanding. Scrape with a flat edge across the grain. You can use a drywall knife or plastic scraper for this. Let dry.
If you are seeking a NOS mirror type finish, I highly recommend grain filling twice with timbermate. If you do use an oil based filler they take numerous coats and sanding before they are perfect. If you are seeking a type of finish like the custom shop where you can visibly see the lacquer has sank into the grain, I recommend grain filling once. If you want all the grain to show, don't grain fill it at all. However, it will never achieve a mirror like finish. Looks good in satin though.
The most important thing to remember is to make sure all of the grain is filled and dry. Sand with 180-220 grit staying with the grain pattern. You can use naptha to clean your work. Once it is filled, sanded, and completely clean, you can proceed to the sealer.
Our sealer is available in aerosol. It is very easy to use and builds to an amazing level barrier between wood and your finish. It is a high solids sealer, so it will fill up any minor imperfections from the grain filling process. Thinner coats are better to build up than super thick coats. Sand between coats if necessary and clean your work using naptha or mineral spirits. Wait at least 1 hour between coats for sanding. Make sure all dust is cleaned up and use a tack cloth before spraying any new coats. 2-3 coats, 1 hour apart.
Applying the primer coat is an important step in the finishing process. If you are finishing your guitar natural, translucent or sunburst, then you do not need to worry about this. Anyone doing an opaque custom colour, primer is used to achieve better colour coverage and spot any imperfections up until now in the finishing process. As with others, start with a light coat. After that, use until you achieve good coverage. Let dry and inspect your work. 2-3 coats, 1 hour apart. If the primer looks rough, you can lightly sand with 400 grit sandpaper. The primer will opaque more with each coat. it may appear light on your first coat. By your 2nd coat you will notice a much more opaque base.
Time for colour. If your primer coat is done we can add colour now. The process is the same. Start with a lighter coat followed by wet coats until full coverage is achieved. 1-3 coats, 1 hour apart. If you have an issue with anything, you can sand your colour coat once dry. Apply more colour if you need to in the affected area. Clean your work 100% before moving to clear. Metallics should not be sanded at all. However, if you have an issue, you can sand it out carefully and re apply colour to get the metallic effect.
After your custom colour is applied, you will want to protect it. For this we use our nitrocellulose clear coat. As for application, it is more of the same. You will use more product in this step though. You will want a good build up of clear for the wet sanding process. If you use to little (or sand too much), you can risk sanding through the clear coat into the colour coat. Legend has it you will want 4-8 coats for a vintage finish and 10-12 coats for a thicker finish. At the Gibson plant they use 8 coats of clear lacquer. Fender is somewhere in the middle. Only sand if you need to (orange peel or a lacquer spatter). Your first coat should again be light. Followed by wetter coats. 2-3 coats per day 1 hour apart.
If you run into any issues in any of these steps ie,,, a run, sag, orange peel or spatter. STOP. Let dry and carefully/gently sand out the issue. Re apply what you were spraying and move on.