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Sanding grain filler: White Spots?

Discussion in 'Finely Finished' started by TelZilla, Jun 14, 2019.

  1. TelZilla

    TelZilla Friend of Leo's

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    So I have a Warmoth Swamp ash body that I'm grain filling. Using this Solarez stuff:
    Solarez.jpg

    Pretty nifty. It cures in the sun in minutes. Anyway, I put several coats on there. First time doing this- honestly I probably put on too much.

    Anyway, I'm sanding it back with a random orbit palm sander and some 220 grit paper. As I sand, I'm seeing these white areas- hopefully it shows on the pix. Doesn't totally obscure the grain, but it's not as apparent as the other areas. It's most prominent toward the edges:
    White stuff.jpg
    white stuff III.JPG

    So my questions are:
    • What are those white areas?
    • Should I keep sanding?
    My guess is that's the solarez, and those are either areas where I didn't get quite as much on there or areas where I've sanded a little more. I mean, if I sanded through to the wood, I'd certainly be able to see the grain. The actual wood isn't washed out like that. So my guess is that I should keep sanding "through" the white stuff till I see something more like wood. Another factor: I'm not making sawdust yet with the sanding, just fine white powder (insert joke), which is the cured solarez stuff.

    What do you think?
     
  2. Buckocaster51

    Buckocaster51 Super Moderator Staff Member Ad Free Member

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    In reflected light, do you see pores in the dark areas and no pores in the white areas?
     
  3. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

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    Did you check the moisture content of the wood before filling? If not - do it now. You can pick up a 2-prong moisture meter for $15-25. It looks an awful lot like moisture entrapment, although there re other possibilities. But this needs to be eliminated right away. If the content reads over 11% it's probably the same thing as lacquer "blush" (over 15% - absolutely).

    The normal acceptable level for coating is 11% - I use 8%. Some take a chance at 15% (if spraying) and keep blush reducer handy.

    Did you do any test runs with the grain filler? What sanding sealer did you use before the grain filler? Are you planning on doing any dye, stain or other grain coloring? What other materials are you going to use? And what grain fillers have you used in the past?

    And did you already do a full test application of the entire coatings system on scrap? That should be done before using any system for the first time - even if changing just one component, you prep, seal, dye/stain/fill (if necessary), apply color or toner oats, clear coats and do final buffing BEFORE applying anything to the real guitar parts.

    It's even a good idea to intentionally mess a few details up so you understand how to fix them invisibly

    Otherwise you have no idea how products work, how they interact, and have no chance to fine-tune your technique. If that hasn't been done I'd stop now, Apply the whole system on scrap until you get it right (if applied correctly lacquer does not ned final surface sanding, just buffing. Sanding is a repair operation.

    Eliminate moisture first, provide the rest of the details and we can try to figure it out while you do your system application on scrap.
     
  4. eallen

    eallen Friend of Leo's

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    I am assuming you pore filled before sealing from the looks of it? If so, in my experience, the light spots looks like you sanded thru to the wood where in other areas there may still be a light layer of fill over the entire surface. The reason you don't see pores is you filled them.

    If you sealed before pore filling as is often done then you may have sanded thru the sealer.

    Eric
     
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  5. Rufus

    Rufus Tele-Afflicted

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    As stated in the last post, my edumacated guess is that you sanded thru the filler/sealer down to the bare wood. Re-grainfill and re-sand
     
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  6. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

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    Solareze - this product - IS "pore filler", or grain filler, or paste wood filler. It's used like Mohawk, Behlens or Timbermate but is a UV-cure product Others are normally used AFTER a coat of sanding sealer.
     
  7. eallen

    eallen Friend of Leo's

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    I think you may have misread what you quoted. I was stating that I assumed he applied it before a sealer, not that he should or shouldn't have or that Solareze wasn't grain/pore filler.

    The point was, in my experience it looks like some areas he removed all the filler except what remains in the grain while in other areas he still has a thin layer remaining above the grain.

    Eric
     
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  8. Jim_in_PA

    Jim_in_PA Friend of Leo's Silver Supporter

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    Try block sanding it by hand and see if things even out. I also suspect that there is filler remaining above the wood surface (darker areas).
     
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  9. Drak

    Drak Tele-Holic

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    220 on a random orbit sander, for me, for sanding back pore filling, is just too much, too fast, too aggresive.
    Re-coat, and (hand) block sand instead.
    You can use 220, I would use 320.
    You could maybe use the random orbit sander with 320 and a light touch.
    But hand/block sanding would be preferred.
    Compressed air is an added plus if you have it.
    If not, a damp cloth wouldn't hurt.
     
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  10. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

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    I agree - and assuming the filler was scraped flush properly using a flexible plastic blade I would ONLY sand with the grain - never cross-grain. Which means absolutely no orbital sander. Those should never be used in finishing - only in body and neck shaping. Should not even be necessary in stripping operations if the proper stripper is used.

    220 Fre-cut or wet-or-dry (not garnet) paper might be ok *if* there's a problem that has been verified to include surface material removal - but if you are unsure I'd never go more coarse than 320.

    I rarely touch anything rougher than 600 in finishing, usually when fixing somebody else's partial job. I use primarily Micro Mesh pads attached to a block with Velcro. Expensive but last almost forever (they wear VERY, VERY slowly), cut faster and smoother, load up less, and flush clean in seconds.

    Any properly used paste wood filler (grain filler) should be able to be lightly sanded with 600 as final "detail work". If rougher paper is needed it usually means there are scraper edge lines (from problems with scraping technique or overly thick material - or both); lumps and inconsistencies - same reasons....and both types of problems generally result from the same overall problem - impatience:

    Lack of ANY practice or test applications on scrap, or not enough to understand how the materials work, how much thinning is required, how many applications are best for a specific cut of wood, how they interact if dyes/stains are used first and/or mixed into the filler, how they react with the previous coat of sanding sealer and the one applied afterwards, what affect the clear coats have on the appearance (especially if the filler was tinted) or if the opaque coats show or hide the grain as desired...

    ...and especially what changes in the application technique thinning etc depending on time of day/temperature/humidity.

    Grain fillers are one product I just can't see being applied properly without SOME practice on scrap. In a lacquer system they are the least likely product that can be applied by "winging it" - but the reality is you have no idea what anything will do or how it will react with other products until you use it, so PRACTICE. not just applying one product you've never used - the whole shebang. prep the scrap piece, seal/stain/dye/fill/seal, apply color or toner coats, clear coats - and if you did ALL that stuff right you should be ready to go right to the buffer.

    If you have to surface sand you are doing repairs. A few minutes with 1500-2000 is OK, but anything rougher and something wasn't done properly - so practice more! At least if you want to do it right. It's worth the time. and small extra amount of material.

    OK, I'm off the Fathers' Day soapbox!

    :lol:
     
  11. Vizcaster

    Vizcaster Poster Extraordinaire

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    As you kept sanding, did the "white" areas get bigger? I think you're truly looking at the wood "in the white" or without any finish or sealer or grain filler at all in those areas.

    My suspicion is that the lighter areas are sanded through, and the darker areas have residual grain filler acting as a sealer on the surface. Try another application of the grain filler (not unusual to have to do it several times) and ease up on your sanding method to cut it back. When you sand too aggressively you cut through to bare wood, and that's even more of a problem if you started with a piece that had been stained because you start removing the stained wood making even more dramatic light spots (don't ask me how I know that).
     
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