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Using DPG instead of Swel-lock

Discussion in 'Axe, Tomahawk, & Hatchet Forum' started by Square_peg, May 18, 2017.

  1. Square_peg

    Square_peg

    Feb 1, 2012
    I feel a little guilty for not sharing this earlier. For several years I've been using generic DPG (dipropylene glycol) on my axe wedges. It makes them hold tight. But here's what I hadn't shared. I mix it with 20% water.

    I stumbled on this amount as a wild ass guess after reading an MSDS for DAP's version, Wood Swell & Lock.
    cedarriverforge.com/Photo-index/axephotos/DPG-Swel lock/Wood-Swell-Lock-DAP-Inc-2000.pdf

    DAP states here that their product contains both DPG and water but doesn't give the percentages. I interpreted this to mean that the water was part of the key to swelling the wood and then somehow the DPG locks the wood in its swelled condition. I guessed 20% water and found it worked well.

    Later I finally found an MSDS for Swel-lock and they confirm that their product contains 71-80% DPG. In another place it suggests they use 75.49% DPG.
    cedarriverforge.com/Photo-index/axephotos/DPG-Swel lock/Swel-lock MSDS B745-4000.pdf
    So here's a heads up. Mix a little water into your DPG. I like to apply it with a dauber which I store outside the bottle so that the water doesn't rust it.

    OK, cat's out of the bag and I feel better. :D
     
  2. Moonw

    Moonw

    Nov 19, 2014
    Well Sir, I am appaled and taken aback...! :eek::eek::eek:

    Honestly, thank you! This may improve my results, tried once, I kind of felt...something was "missing", as the outcome was more modest than I would've expected.
     
    Square_peg likes this.
  3. Old Axeman

    Old Axeman

    337
    Jan 10, 2015
    Square_peg--Do you think the water might act as a catalyst for the DPG ?
     
  4. Square_peg

    Square_peg

    Feb 1, 2012
    I don't think so, at least not in the sense of starting or supporting a chemical reaction. If that were the case if would go off as soon as the products were mixed. I suspect the water is getting inside the wood cells and swelling them, then somehow the DPG is causing the cells to remain enlarged.
     
  5. 300Six

    300Six

    Aug 29, 2013
    DPG is supposed to substitute for the displacement of moisture in wood which then makes it more stable. Perhaps the function of the water in Swel-Lock is to 'swell' dried out wood in advance of being displaced by the glycol. I'm guessing that DPG, on it's own, then isn't able to cause wood to expand.

    Be an interesting test to do on some green wood and some dry wood samples and easy enough to confirm some time later with a set of calipers.
     
  6. Old Axeman

    Old Axeman

    337
    Jan 10, 2015
    SP & 300Six--those answers make a lot of sense to me, Thanks
     
  7. 300Six

    300Six

    Aug 29, 2013
    To me too! Lee Valley Tools was flogging both a version of swel-lock (for tightening-up loose chair legs etc) and DPG (for avoiding curing checks and splits in green wood) in the mid 1980s when I was trying to figure out a way to keep decorative tree trunk X-sections from severely splitting as they dried out. DPG was overly expensive and resulted in an unattractive grey/green colour so I took to bathing my sections half-submerged in a garbage can lid of furniture oil (teak & tung; which is probably 90% BLO). I surmised that; as the moisture wicked out of the exposed surface the oil would move in from underneath. This worked perfectly well for me and if pictures are necessary (I still have a few examples from 1987) I can post them.
     
  8. Park Swan

    Park Swan KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    543
    Mar 15, 2016
    I'd love to see pics! Encountered this same puzzle as a sculpture student but could never afford any solutions :)
     
  9. 300Six

    300Six

    Aug 29, 2013
    I prepared quite a few of these slabs over the years with various types of wood. Shown below is maple. The wood was fresh cut (ie within 24 hours) at the beginning of the treatment and here we are 30 years later. The furniture oil used happened to be Circa 1850 brand 'Teak & Tung' but I'll bet it's mostly BLO despite the name.

    [​IMG]

    [​IMG]
     
  10. Square_peg

    Square_peg

    Feb 1, 2012
    That's fantastic, 300! How long did you leave them in the oil?
     
  11. 300Six

    300Six

    Aug 29, 2013
    Probably a month or so. I would have kept at it until the wood would no longer take up anymore oil. This is easy enough to determine when you use a shallow dish.
     
  12. Park Swan

    Park Swan KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    543
    Mar 15, 2016
    Those look awesome! Now I remember that I did do that with some smaller pine cutoffs wit particularly nice coloration for a set of coasters. I just used mineral oil, they didn't cracking but jt was pretty gross because mineral oil is gross and it seeped out for a while.
     

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