sanding sealer

Discussion in 'Woodturning Discussion Forum' started by Max Taylor, Nov 22, 2014.

  1. Max Taylor

    Max Taylor In Memoriam

    Joined:
    Dec 26, 2005
    Messages:
    185
    Location:
    FT. Worth,Tx.
    seems to me that the work piece needs to be blown out with compressed air after each grit of sanding. Otherwise the dust gets in the pores and eventually becomes part of the turning. As I understand sanding sealer is supposed to prevent this. Could someone with more experience elaborate on this subject? When and where to use, etc. Thanks, Max
     
  2. John Tisdale

    John Tisdale

    Joined:
    Apr 11, 2014
    Messages:
    106
    Location:
    Dallas, TX
    I assume from your question that you're after a "flat" finish rather than a more organic finish that has a tactile feedback of real genuine wood.

    Never confuse "filling" with "sealing"

    I use thickened epoxy for most filling and consider it part of the turning process. I put it on, let it dry and turn it off.

    Sanding sealer is for filling pores - I spray it on (never on the lathe), let it dry, and then sand for a "flat" surface. My definition of "flat" is without orange peal, pores, etc. Sealing is part of the finishing process and, to may thinking, should not be applied on the lathe nor sanded on the lathe. While that may be canon for my stuff, I know that lots of guys get great results applying wipe-on lacquer sealers on a running lathe. These dry fast and may be sanded soon after. Again, to my thinking, finish sanding on the lathe results in annular grooves that detract.

    The above is my opinion and, while highly unlikely, I could be wrong
     
  3. odie

    odie

    Joined:
    Dec 22, 2006
    Messages:
    4,420
    Location:
    Deep in the woods
    Max.....Sanding sealer may prevent dust in the pores, but that's not what the intent is. My thoughts are similar to John T's.....Sanding sealer is to seal the pores, and not intended to be part of the surface preparation.

    Yes. a good ol' blast of air takes care of 99% of the dust in the porous surface, and a tack cloth will also help.

    Regardless, I'm one who thinks the pores of natural wood are a subconscious aesthetic appeal to the observer. Because of this, I'd rather have the porous surface, but there is the possibility that, at some future point, the bowl could be ruined by some staining liquid spill. To my thinking, the pros outweigh the cons.......

    ko
     
  4. hockenbery

    hockenbery AAW Advisor Staff Member

    Joined:
    Apr 27, 2004
    Messages:
    4,304
    Location:
    Lakeland, Florida
    Home Page:
    Max, If you do any thin turnings, be aware that a blast of air can blow a hole in the turning.

    On occasions I use a thin shellac ( twice the alcohol) which sort of acts as a sealer.

    On punky wood I use it to stiffen the fibers and get a cleaner cut and then to stiffen the wood for sanding.

    I usually put the thin shellac on walnut sapwood to keep it white. It reduces the chances that the heartwood dust can discolor the sapwood.

    If I want a piece to have a shiny finish I will often use the shellac before sanding with 320. Then I get a nice build up with 3- 4 coats of waterlox that might be equivalent to a 6 coats without the shellac.
     
  5. hockenbery

    hockenbery AAW Advisor Staff Member

    Joined:
    Apr 27, 2004
    Messages:
    4,304
    Location:
    Lakeland, Florida
    Home Page:
    Max,
    A couple of other times a sanding sealer is needed

    If you are working with color or vacuum chucking you may want to seal the surface instead of finishing it.
    Stains and dyes will bleed through many woods and if you do not wish to have the opposite side colored sealing the opposite surface prevents Bleed through.


    If you sand a bowl of a vacuum chuck, dirt will pull through the poors of some woods leaving a "bath tub ring" you can never get rid of.
    Finishing the inside of the bowl first or putting on a sealer will prevent the dirt ring. This can happen on cherry and soft maple.
    And can be really bad if you wet sand.


    Al
     
  6. Gerald Lawrence

    Gerald Lawrence

    Joined:
    Feb 6, 2010
    Messages:
    719
    Location:
    Brandon, MS
    Use of sealers depends on what you want the final finish to look like. If you want a high gloss finish the sealer helps to give you the build faster. Sealers can also help to prevent change in color to the turning caused by the penetration of the final finish into the pores of the wood as Al some what indicated to stop the sanding dust from discoloring light areas. The principles of build is more familiar to flat work finishes than to turners, as turners do not often use these techniques.
     
  7. john lucas

    john lucas

    Joined:
    Apr 26, 2004
    Messages:
    5,822
    Location:
    Cookeville TN USA
    Sanding sealer is also good for preventing colored woods from staining white woods while sanding. the worst example I can think of is Padauk next to holly or maple in a segmented turning. Apply the sealer before sanding, and then before each new grit. In other words, sand, dust it off, apply sealer and sand with the next grit.
    Sanding sealer has a stearate in it to help keep the sandpaper from clogging which is what it was designed for (at least that's what I've read). Because of that it isn't the most clear of finishes so it's not the best thing to use to build a finish. It does help fill the pores slightly so it's easier to blow the dust out of the pores for the next coat of whatever finish you use.
     
  8. Bill Boehme

    Bill Boehme Administrator Staff Member

    Joined:
    Jan 27, 2005
    Messages:
    8,122
    Location:
    Dalworthington Gardens, TX
    Home Page:
    Max, I believe that you are thinking about grain filler rather than sanding sealer. Grain filler is sometimes used in flat woodworking (furniture kind of stuff) when you want to fill large pores in wood such as ash or red oak. It is similar to pigment wiping stains, but a little more heavy bodied and not much pigment and dye.

    A sanding sealer is very similar to the topcoat except that it is softer, has more solids, and dries quicker than the topcoat. It is meant to be applied AFTER you have completely sanded the bare wood and are ready to apply finish. The sanding sealer should be sanded smooth with 400 or finer grit paper to prepare the surface for the topcoat. It will help to seal the tiny pores so that the topcoat won't soak into the end grain as much as it would if it were applied directly to the bare wood. If the wood has medium or large pores, sanding sealer won't help to fill them. The sanding sealer needs to be compatible with the topcoat -- in other words, don't apply a polyurethane topcoat over a lacquer sanding sealer. If you are working with mesquite, it sometimes has fairly large pores in the end grain, especially if there is a lot of figure in the wood and sanding sealer won't completely seal the pores if that is what you want to do.

    There are some friction finishes that may be the best route to get a smooth glossy finish without a lot of work.
     
  9. Bill Boehme

    Bill Boehme Administrator Staff Member

    Joined:
    Jan 27, 2005
    Messages:
    8,122
    Location:
    Dalworthington Gardens, TX
    Home Page:
    BTW, Max, I have been sanding a large box elder bowl this evening and a lot of dust does get into the end grain pores. I just use a shop vac first and then use compressed air to get the rest of the dust. If there is any dust remaining after that, I am fairly certain that you won't see it after the finish is applied.
     
  10. john lucas

    john lucas

    Joined:
    Apr 26, 2004
    Messages:
    5,822
    Location:
    Cookeville TN USA
    Not sure whether he's wanting to fill the pores or not. For a more natural look I leave the pores unfilled but on those pieces I don't use a glossy finish. More of a satin.
    If I want to fill the pores there are many ways to do it. One is to sand with a finish and let the sanding slurry fill the pores. At least somewhat. It takes quite a few coats to do this.
    You can also use some kind of pore filler. This is usually a sort of thickened compound. Pumice mixed with oil is used by some.
    Another way is simply to apply a high build finish. Sand it down to bare wood and then apply more. Each coat fills the pores a little. Eventually you have them all filled and then you can get that glass like finish. The fastest way I've found to do this is to use Birchwood Casey's True-oil. It does darken the wood quite a bit on lighter woods but it builds quickly and leaves a very nice finish that takes very little polishing to get a glass like finish.
    Some of course like to use a contrasting filler to really make the pores pop. I have used plain old shoe polish for this with a shellac sealer over the top. I've also used colored chalk and tempera paints mixed with various mediums like lacquer, oils or even epoxy to fill the pores.
     
  11. Max Taylor

    Max Taylor In Memoriam

    Joined:
    Dec 26, 2005
    Messages:
    185
    Location:
    FT. Worth,Tx.
    Hi all, I didn't fully explain what I am trying to do. If you are familiar with Spectraply you will know what my problem is. After shaping a peppermill if you even have sandpaper in your shop, it will send tiny particles of dark wood into light wood , and the only solution is to repeat the finishing cut to clear it up. I cannot make a finish cut smooth enough to not sand it. Therein lies my problem. I thought sanding sealer would solve it, but nooo. Maybe some of the suggestions given here will do the trick. Hope so anyway. Max
     
  12. Bill Boehme

    Bill Boehme Administrator Staff Member

    Joined:
    Jan 27, 2005
    Messages:
    8,122
    Location:
    Dalworthington Gardens, TX
    Home Page:
    Max, you might consider using Minwax Wood Hardener, but it makes wood so hard that turning it becomes a real chore.

    Another idea is to use super thin CA to seal the wood. My main problem with CA is gluing my fingers to whatever I am working on. I've started using nitrile gloves which do not stick if you get CA on them.

    I don't know if either of these will cause the colors to bleed because they do have some pretty potent solvents so I would practice on some scrap wood.

    Also, I agree with what John said that sanding sealers aren't very clear. They use zinc stearate which is a very fine white powder that acts as a lubricant in sanding and prevents corns from forming on the sandpaper as John said. The problem is that the zinc stearate makes the sanding sealer slightly cloudy. It usually isn't noticeable on a natural wood finish, but I accidentally used some on a dyed platter when I thought that I had picked up a can of gloss lacquer.
     
  13. john lucas

    john lucas

    Joined:
    Apr 26, 2004
    Messages:
    5,822
    Location:
    Cookeville TN USA
    Max I think I mentioned it above. Use the sanding sealer first and then between every grit. Blow it out if you have a compressor or dust if off after each sanding and before applying the next coat of sanding sealer. I fought that same problem many times. That method works as good as any that I've tried. It is a pain in the butt but it works.
     
  14. Bill Boehme

    Bill Boehme Administrator Staff Member

    Joined:
    Jan 27, 2005
    Messages:
    8,122
    Location:
    Dalworthington Gardens, TX
    Home Page:
    What kind of sanding sealer and how long does it need to dry between coats?
     
  15. Raul McCai

    Raul McCai

    Joined:
    Oct 29, 2014
    Messages:
    416
    Location:
    nj
    The sanding sealer that I use is a General Finishes product. It's a water based sealer that is supposed to reduce the grain raising so that I apply it once, do a light sanding and can then apply the water based finish that GF also sells. Failing to apply a sealer under a water based finish causes me to have to sand the raised grain at least twice.

    Shellac is more certain sealer than the GF product in my experience.
     
  16. Mjonesrdg

    Mjonesrdg

    Joined:
    Aug 20, 2007
    Messages:
    48
    Location:
    Redding, California
    Sanding Sealers

    Max, I suspect that your peppermills are finished, wrapped, and out the door by now, but if not, I hope to clarify a bit for you and others. Lacquer sanding sealers, like Deft* or Mylands*, contain stearates that make sanding easier and helps to prevent clogged sandpaper, but will appear cloudy in the container only. That is, the sealers will dry water clear. (cloudy lacquer coats usually means too much moisture in the air while spraying).

    When your work piece has contrasting colors, as with your Spectraply*, the fine dust particles tend to migrate and unwanted blends are created. The way that you apply your sanding sealer will have much to do with the way that it "works" for you to solve the problem. John Lucas has it right, but I would add, that the idea with each "coat" is to literally flood the wood with sealer, and as some of the "thirsty" areas absorb the sealer, keep those areas wet. Keep adding sealer until you have a sticky mess forming, then, immediately wipe off the excess. It will be dry to touch in 10-15 minutes...then repeat the above procedure. Wiping it dry will relieve you the requirement to sand before the next coat.

    Lacquer sanding sealer may be top-coated with any varnish, (including polyurethane), shellac, or finish lacquers
     

Share This Page