TL- sanding step by step

[Laforet99]

Spent 3 hours sanding and sanding.
Finished at 240.

https://ibb.co/NsRSHPm

[Laforet99]

i sanded till 320, then i stained the guitar.
some parts seem to have lost their sanded smoothness after the staining process.
what should i do now?

[jugglindan]

At the risk of being completely wrong, I suspect that is loose wood fibres standing up in response to the moisture in the stain. However, I cannot give any advice on the right sandpaper grade to use for very gently removing them, as I have no experience sanding stained timber.

With my build I lightly wiped down the body with a damp rag, waited for it to dry, and then lightly sanded at 5 degrees off the grain to knock off the loose fibres. But this was prior to applying any finish.

[Laforet99]

yes you are right is the reaction to the moisture. So the max grit i had was 320, i gently sanded to recover the smooth touch, it went well.

i applied a first layer of transparent mat laquer in spray, looks ok, but needs more layers.

i don't know how long i have to wait before it dries.

[McCreed]

You are both correct in that the stain (whether oil-based, water-based, alcohol-based) will raise the grain fibres and the remedy is indeed to knock it back with a very light abrasive as you've done.

I use fine synthetic sanding pads (sometimes referred to as "synthetic steel wool"). Some people use actual 0000 steel wool, but I find the near microscopic steel fibres that result an absolute nightmare to deal with for whole host of reasons.

In regard to your rattle can spray lacquer, you can re-apply while it's still just slightly tacky (before it reaches "touch dry") or, if it does get to the point of touch dry, leave it overnight. The next day: lightly abrade the previous coat (I wouldn't go coarser than 240); remove ALL the dust (blowing or vacuuming); apply next coat(s).

With spray can acrylic lacquer, if the coats go beyond touch dry, you need to abrade them to create a mechanical bond. There is an amount of chemical bond with spray can acrylic, but not like nitro or "hotter" lacquers.

Once you have all the coats of clear you want (I suggest at least 4-5) you need to leave it for at least 14 days before you start sanding back to level & polish. This part of the process is where patience is truly a virtue and probably the most difficult step.

You'll really hate yourself if you rush it and stuff up all the hard work you've put in thus far. I know this from experience

[Laforet99]

hi,
ok so i put 6 coat of mat spray laquer, with a 1 hour drying period between each coats, and a light very light sanding between each coat too, with 320 grit, the max that i have.


So as i anderstood the next step is polishing, but with what?

[McCreed]

Sorry, I missed the "matte" finish bit.

You may not need to sand your final coat presuming you got a nice flat finish on the last coat (no runs, sags, orange peel).
If you got any defects like that (that you can't live with) you'll need to fix those by sanding them flat then re-spray and try not to repeat the mistakes.

If your existing final coat is all good, then it might just require a slight bit of wet sanding to just knock off any dust nibs. The idea is to just smooth it, not polish it IYKWIM. You probably wouldn't need anything finer than P800 or possibly just a light hit with a fine sanding pad or steel wool. (see my previous post)
However, I would still wait the 14 days before doing this.

[Laforet99]

it's all flat and smooth, i'm planning to just polish with some polishing cream and an old rag, that's all the equipement i have. And yes i'm planning to way several days... 14 days seems to be a long period to me, but i'll try.

[Simon Barden]

14 days is the bare minimum. Wait another week and the result will be even better as the finish will be even harder.

Even for a matt finish, you still want the finish to be flat, so hold the body up to a light at a shallow angle. This will clearly show up any small dips in the finish that are still shiny. You want to keep sanding back until those dips are all gone.

But if you want a matt finish, I really wouldn't think about polishing it, as it's very easy to buff it up to a shine. But I would use some finer grit papers. You really don't want to sand back with anything coarser than P400, and you'll probably want to sand up to P2000 to get a satiny finish. If you polish it, then probably no more than P800, as you'll then get a semi-gloss look.

Don't use furniture polish (most contain silicone which is impossible to remove and makes and further painting/touch-ups impossible), use a paint rubbing compound like Meguires or T-cut.

[Laforet99]

it's done.