First bass build. NOT A CLUE about sandpaper.

Discussion in 'Luthier's Corner' started by Juani Vitale, Oct 28, 2020.


  1. Juani Vitale

    Juani Vitale

    Jan 27, 2018
    Argentina
    Hi bass people! Let me give you some insight. I already own a couple of P basses but Im building a 3rd one out of parts. Just ordered a "raw" P bass body and neck and I'm planning to do pretty much everything else on my own without a lot of pro tools (no pun intended). I bought some nitro cans for the finish (white primer, black nitro and clear coat, transparent for the body and an extra amber one for the neck). I also bought some boiled linseed oil since i saw some luthiers recommending it for wood conditioning.

    I'm still not completely sure if Im going to paint black or leave it a natural finish. It will probably depend on how the wood grain looks for me (the parts are yet to arrive). My plan (based on ZERO experience/knowlodge) was to first see if I can slightly darken the wood using some kind of water-based stain, then "finish" the body with the oil first and then depending if I like how the grain looks or not, give it the primer/black/clear coat treatment or going straight for the clear coat.

    The thing is I'm completely lost on the sandpaper subject. Can you guys guide me on what type and grit of sandpaper to use for before/after all of those stages I mentioned? and also in wich of those stages is necessary to sand.

    Thanks a lot for the help!!
     
    Last edited: Oct 28, 2020
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  2. daveman50

    daveman50 Supporting Member

    Feb 24, 2007
    Albany NY
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  3. Beej

    Beej

    Feb 10, 2007
    Vancouver Island
    Your new body will probably come sanded at least somewhat. If it's not sanded at all, then start with around 120 grit and work your way up to 220. Increments for sanding wood are usually something like this: 120, 150, 180, 220, 280, 320. This depends on how smooth it is to start. If it's rougher, raw lumber or has planer marks on it, then you can go as low as 80 grit, then 100, then 120, etc.

    Some folks jump between the grits, so from 120 right to 220, etc. That's okay, as long as the 220 is removing all of the scratches from the 120. There is usually not much to be gained by going higher than 220 if the wood will be sealed and finished, but that said, I like to sand bodies to 320 myself.

    A couple of pointers:
    1. Always sand with the grain. If the grain goes across the body at an angle, sand following the grain lines. Any cross-grain sanding will introduce fine scratches that are highlighted as you go. Sanding with the grain helps eliminate these.

    2. Always sand flat surfaces with a hard sanding block. I like to make MDF blocks and staple sandpaper to them so they are a perfectly flat sanding surface. You simply cannot sand a flat surface with fingers - it will make little bumps, dips and undulations across the surface. Block sanding is the only way to get things perfectly flat.

    3. Use quality sandpaper. I highly advise against using inexpensive sandpaper - it's often a mix of grits and near impossible to get a smooth surface with all previous scratches removed. :)

    When sanding a body, I usually start with the sides by hand - I wrap a small piece of sandpaper against a piece of 1/4" thick leather, but you can do it by just folding the paper and holding it in your fingers as you go around the body. Sand with the grain, right up to the top/back, but not over the edge. When the sides are sanded, then do the top/back with a hard block. Do this same process for each grit as you get up to 220.

    Once you reach 220, it's important to start grain-raising to ensure the surface is baby-butt smooth. I raise the grain by wiping the whole thing down with a damp cloth (water) and letting it dry. This cause expansion of the wood fibers, and raises small fibers of wood up and permits you to sand them back smooth again. I usually raise the grain at least three times between 220 and 320. The difference between a grain-raised sanded surface and one that is not grain-raised is striking when it comes to final smoothness.

    I also wear gloves in this whole process as finger oils can mark the body and potentially contaminate the surface for later finishing.

    So this above is all just sanding of the wood, not the finish schedule, I can add my thoughts to another post. :D
     
  4. dwizum

    dwizum

    Dec 21, 2018
    Practice! On scrap! Learning to sand or finish on a real bass will be like learning to drive by jumping on the freeway at rush hour.

    For products, I like to keep it simple. I have round foam sanding pads and blocks made to fit the same velcro backed 5" disks that my random orbit sander uses. So probably 80 or 90% of my sanding is with Mirka Gold 150 or 320 grit disks. I also use 400 and 800 grit Abranet disks for really fine sanding and finish work. For leveling flat surfaces I have a 14" long maple block that I can screw lengths cut from 3" wide rolls to (the same rolls my drum sander uses). And I also have two big (12" by 22" or so) pieces of 1/8" hardboard, one with 80 grit and one with 120 grit, which I use when I want to flatten or sand smaller stuff by laying them on the bench and using them like a "sanding table" where you rub the part against the table instead of the sandpaper against the part.

    These are the sanding "blocks" I like with the disks:

    https://www.amazon.com/dp/B07XXNRJ15/ref=cm_sw_r_cp_apa_i_xBWMFb4JT9MYE

    And these are the soft pads:

    https://www.amazon.com/dp/B07C1R3NXN/ref=cm_sw_r_cp_apa_i_lCWMFb0C12W5F
     
  5. T_Bone_TL

    T_Bone_TL

    Jan 10, 2013
    SW VT
    I would just add to vacuum or otherwise clean between grits - a loose 80 grit particle being rubbed around by your 120 grit paper makes a hash of your sanding process. That includes making sure the sandpaper you pick up isn't contaminated.

    At some later point in time you might want to learn about scrapers and the extent to which you can skip right past sandpaper (or use a lot less of it) if you learn to use them well, but probably not a good place to try and start.
     
  6. Juani Vitale

    Juani Vitale

    Jan 27, 2018
    Argentina
    Thank you guys, you've been very helpful. Parts are yet to arrive (COVID) but I'll probably share some pics of my progress once I begin working on it!
     
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  7. Gilmourisgod

    Gilmourisgod

    Jun 23, 2014
    Cape Cod MA
    I aint got much, those guys nearly said it all. Ive done some special inlays that required some super high grit polishing, which is usually a waste of effort on wood. If you get into anything really high polish, check out the Micromesh pads, excellent stuff. Ive also had good luck with Mirka Abralon and Abranet, but thats more tailored to finish work like sanding and buffing paint. The vacuuming advice is key between grits, otherwise you are just grinding in the scratches.
     
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  8. dwizum

    dwizum

    Dec 21, 2018
    Micro mesh pads are awesome. Everyone should have a set. They can get you to an exact level of matte/gloss on any hard polish-able surface. Really good for blending finish repairs and trying to match an existing finish. And also good for polishing/cleaning up small hard parts like nuts. And you can use them on frets too. I had a guitar where I wanted a nice clean finish on the frets but I wanted to stop at a semi-gloss instead of a full polished gloss, to match the satin hardware. The micro mesh pads worked great for that. They last a long time and can be washed out so you don't contaminate different materials. Really great stuff.

    I love Abranet, too! The disks are expensive but they outlast normal sandpaper by a long margin (like, five or ten to one probably). And they don't load up even when dry sanding. Really great for finish work, especially when finishing a surface you don't want to wet sand.

    While we're on the subject of non-sandpaper abrasives, I would suggest getting some scotchbrite pads as well. I would start with the gray and white. They're a good alternative to steel wool and work great for general cleaning/scuffing. I use the white pads to apply wax when waxing/buffing satin finishes. They're good for cleaning/polishing fretwork. You can cut them to any size/shape you need.

    All that said, I'm buying sanding materials to make a dozen or two instruments a year, so it makes sense for me to get all these specialized materials. If you're starting from scratch and building one "kit" instrument you probably don't want to go blow $100-$200 or more just on different variations of sandpaper! You'd be fine getting some plain sheets of 120, 180, and 320 (or whatever's close to that at your local hardware store). One or two sheets in each of those grits for a single instrument. And then maybe a sheet or two of 400 or 600 wet/dry for scuffing in between finish coats, and something to polish or buff your finish depending on the finish material you're using and the sheen you want. Get one of those cheap hard rubber sanding blocks and a soft foam pad and you're all set. Probably more like $20 out the door. And then you can build from there if you get bitten by the bug (which, trust me, you will).
     
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  9. Nothing really new to add but I would echo the sentiment to use good sandpaper. Home Depot has the red 3M paper, see the picture. That would be sort of the minimum, easily available paper. I think HD might also have 3M Free-cut, something like that, which is good to. With my random orbit sander and I have a sanding block that uses the round ROS pads I’ve been using either Diablo, from HD up to 400 grit or Abranet pads. As stated, they last longer then standard sandpaper and blow or vacuum out easily.

    Keep us posted on the project!

    image.jpg
     
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  10. Arie X

    Arie X

    Oct 19, 2015
    in addition to all of the above, FWIW, i would suggest to stick with one grading of paper either FEPA or CAMI on a project as there are differences between the two. FEPA paper uses a "P" prefix as in P80, P100, etc... CAMI does not. I tend to use FEPA only because I have a lot of it. Either will get it done, but mixing the two up on a task might not be the best idea.
     
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  11. T_Bone_TL

    T_Bone_TL

    Jan 10, 2013
    SW VT
    Somewhere (presumably findable on the web) is a chart that shows the relationship of the two, but sticking to one or the other is simpler, yes.
     
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  12. Arie X

    Arie X

    Oct 19, 2015
    to add ime, if using a clear finish and clarity and depth is one of the things you'd like to enhance, consider using a scraper for final. these tend to cut wood fibers rather than abrade them into fine hair which can make clarity and depth look a little less than. if you're painting with color, then don't bother -usually, but scrapers can make a flatter looking surface if done right.
     
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  13. Arie X

    Arie X

    Oct 19, 2015
    Sandpaper Grit Chart – WoodBin
     
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  14. Juani Vitale

    Juani Vitale

    Jan 27, 2018
    Argentina
    Well Im already stocking myself with some sandpaper. Body and neck are supposed to arrive next week. Can't wait!

    I'm going for a classic 60s P bass look (although with a "custom" finish) but the hardest decision for me to make right now is that body finish. I know that's a 100% personal and subjective choice and you guys can't "help" me with that, but maybe you can throw in your own opinions just for conversation (not sure if I should open a different thread for that tho...)

    I've got two favourite options and I just can't decide between them:

    1. Give the wood a slightly darker dye and then apply a clear nitro coat. So it would look something like this. Then give it a light relic treatment, paint checking and stuff.
    2. Paint it with white primer and black nitro (already have those cans) and give it a heavy relic. Something like this, but probably even more beat up.

    (I already have an original Fender tort pickguard, and those things are f*****g expensive, so both options would be based on that :laugh:)

    I'm a sucker for old looking instruments. I do know that relicqing is a divisive subject but I really love how it looks. My preference for that is not to try to "fake" real wear and marks, but rather make it look really apocalyptic and almost unrealistically worn and thrashed (a la John Mayer's Black 1 strat) or not really do it at all.

    what do you guys think about this?

    Thanks for all the sandpaper help btw!!
     
    Last edited: Nov 10, 2020
  15. dwizum

    dwizum

    Dec 21, 2018
    For me, an "old looking" Fender-style instrument pretty much has to be solid painted. So of your two options I'd go with the second. Since you already have primer, black nitro, and clear coat you should be all set.

    I'd skip the linseed oil. You don't really need that as part of a nitro finish process and it can cause problems (namely, it takes a long time to cure fully, and rushing your nitro over top of uncured oil would be a mess). Depending on the wood choice for the body you may want a pore filler (since solid painted colors are typically done flat versus with the pores showing).

    The reranch website has a great section on finishing basics which focuses on nitro:

    Guitar ReRanch ~ Basic Refinishing

    Nitro can be tempermental to put down well, and it is fragile. Plan on lots of practice on scrap to hone your technique. Although if you're doing a relic effect, none of that may matter.
     
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    Primary TB Assistant

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