sodium silicate as a wood filler?

Discussion in 'Materials' started by teakcell, Mar 26, 2009.

  1. teakcell
    Joined: Jan 2009
    Posts: 54
    Likes: 2, Points: 0, Legacy Rep: 17
    Location: myanmar

    teakcell Junior Member

    Would anybody have experience/idea/advices on the pros and cons of using liquid sodium silicate as a wood filler prior to varnish (instead of wood filler)?
    Many thanks in advance for any coming information.
     
  2. mydauphin
    Joined: Apr 2007
    Posts: 2,164
    Likes: 53, Points: 48, Legacy Rep: 575
    Location: Florida

    mydauphin Senior Member

    What happens when Sodium silicate gets wet? Oh...
     
  3. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 485, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Interesting idea, though you have to drive out the moisture to get it to harden. This can be done at around the boiling temperature of water. Once hardened, it will need 1,500+F to melt it.

    Unfortunately it's very brittle and unless it's "roasted" to make it "gel" it will reabsorb moisture. Once it becomes hardened it will likely pop right out of a repair area with moisture content changes in the wood.

    Magnesium silicate might be a better choice.

    Both could be used in suspension as a particulate (filler) in a resin matrix, magnesium silicate commonly is employed this way.
     
  4. Boston

    Boston Previous Member

    so what would the proper filler be for marine use
    cheep easy readily available and durable
     
  5. peter radclyffe
    Joined: Mar 2009
    Posts: 1,419
    Likes: 64, Points: 58, Legacy Rep: 680
    Location: europe

    peter radclyffe Senior Member

    sawdust, it wont give you silicosis like silica fillers might
     
  6. Boston

    Boston Previous Member

    I like that one
    I use sawdust and varnish as a filler on my furniture builds and my architectural woodwork

    back in the day old Robby used to use copper paint and sawdust on the body and varnish and sawdust on the top sides and interior

    would have thought they had something better by now but apparently no go
    Im ok with that
    as it fits all the above criteria
    thanks
    B
     
  7. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 485, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Saw dust has it's limitations, though it also has it's uses. Dust from a sander is usual too course to make smooth fillers. You have to use ground wood dust.

    There are lots of different things you can use as reinforcements in epoxy. Silica is one of them and with a dust mask you will experience no ill effects. I use a lot of milled fibers and silica. Most often the filler mixture is a combination of several particulates, each providing a specific quality. No one material or mixture is suitable for all uses.
     
  8. peter radclyffe
    Joined: Mar 2009
    Posts: 1,419
    Likes: 64, Points: 58, Legacy Rep: 680
    Location: europe

    peter radclyffe Senior Member

    I agree, there are very expensive chemical fillers, awlgrip , boero, tombstone, kicked bucket finishing co, etc, but people use more fillers today than ever, especially on metal hulls, because its cheaper to use fillers than to learn how to weld properly, in europe at least, I cant say for other places, some of the yards in Viareggio will use 8 or 9 inches of filler on a steel hull, at 50 to 300 euros per sq meter, on one boat one guy was looking along a 40 meter hull before filler & his mate was standing in a weld distorted recess, his back to the hull , & his mate could not see him.
     
  9. mydauphin
    Joined: Apr 2007
    Posts: 2,164
    Likes: 53, Points: 48, Legacy Rep: 575
    Location: Florida

    mydauphin Senior Member

    Use epoxy... There are some that are very liquidity, thinner than water and there some jelly like, others like peanut butter.
    If a gap is big, I build a wall with some thin material, pour liquid, then add a little sand, fibers, then more liquid. Remove form, then fair with peanut butter like epoxy or jelly depending on gaps left. These repaired piece are indestructible. If the hole is really big I used sawdust with epoxy. the options are endless.

    Describe what you need and I will tell which one to buy. It is not cheap, but will last longer than the rest of your boat.
     
  10. apex1

    apex1 Guest

    That exactly is not possible................ He cannot go next door and buy. And he uses Epoxy every day! So there must be a reason why teakcell asked for the sodium stuff.
     
  11. Boston

    Boston Previous Member

    the sawdust trick can have shrinking problems as well and oft requires several layers
    obviously depends on the depth of the defect your working on
     
    Last edited: Mar 30, 2009
  12. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 485, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I could go into what each materials adds to an epoxy resin matrix, but the list would be long and unnecessarily tedious to compile.

    Wood dust (not saw dust) makes a fairly good glue, but there are areas you don't need glue or you need something considerably stronger.

    With structural fillets for example, I routinely use a 40% silica, 50% milled fibers and one or two different color and/or smoothing agents to make the fillet "lay down" clean, smooth and easily covered with tape or prepped for paint. If I used wood dust, I wouldn't get as good a bond with the substrate, though it would be easier to sand and the color might be close to what I'm working with.

    Some reinforcements (filler materials) are thickening agents, other used to "bulk up" the epoxy, still others designed to be extremely light weight (like micro balloons or Q cells). It depends on what your needs are.

    Very rarely I'll use just one material in a batch of goo. I'll use the reinforcements that do the best job for the tasks I'll be asking of the cured finished product.
     
  13. teakcell
    Joined: Jan 2009
    Posts: 54
    Likes: 2, Points: 0, Legacy Rep: 17
    Location: myanmar

    teakcell Junior Member

    all your answers fully appreciated.
    If you know a list of all materials adds to epoxy commonly available, please let me know.
    Thank you very much indeed.
     
  14. mydauphin
    Joined: Apr 2007
    Posts: 2,164
    Likes: 53, Points: 48, Legacy Rep: 575
    Location: Florida

    mydauphin Senior Member

    PAR is 100% right... and Epoxy is a learning experience... Learn by experimenting until you get a feel for it. Sometimes, I add stuff just to see what happens or to lighten it. For example, Epoxy and cotton is a hell of tough mixture, had a little sand, colored talc and can make a one off item that are indestructible. Been playing with using concrete coloring powders to make unique colors.

    In other words application determine mixture, also remember Epoxy has one Nemesis ... UV... Anything exterior I paint... Even suppose UV epoxied lose coloring, gloss and strength over time.
     

  15. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 485, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Teakcell, you're best bet to get a handle on some of the commonly used reinforcements in epoxy, is to log onto the sites of the major epoxy formulators. Each has a "user's guide" that can be downloaded. They also offer different materials in bulk, though it's not the most effective method of purchasing them.

    These will be the most commonly used materials, but many others are also used. Shredded cotton has been mentioned, which produces a very tough glue and fillet material, but is also very difficult to sand smooth, which is one of the reasons you'll use more then one material in the matrix.

    Uses generally fall into a few different categories; coating, light fairing, heavy fairing, light gluing, heavy structural gluing, cosmetic filleting, structural filleting, laminating and bonding (different from gluing).

    For each of these tasks and each substrate you're working with, you'll use different combinations of materials. The most common of these will be covered in the "user's guides" offered by the epoxy formulators.
     
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.