keepinng finishes from gelling

Discussion in 'Tutorials and Tips' started by john lucas, Mar 23, 2014.

  1. john lucas

    john lucas

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    I've had terrible problems with miniwax wipe on poly and other hardening oil type finishes. I tried the various sprays that displace the air in the can and maybe it helped but not enough. My finish still gelled.
    Then I tried decanting it off into smaller containers but still had trouble removing all the air and it eventually went bad in the small jars.
    I've tried eliminating the air using marbles to take up the space. That's a pain and you have to find something to do with the marbles each time you buy a new can.
    I tried putting saran wrap on top of the finish before putting the lid on the containers. It seemed to work but is messy and the finish will still gel in the small containers when half used if you don't put the saran wrap on top every time.
    I think I finally have the solution but haven't put it to a full test yet. I bought some Coghlan's Squeeze tubes for storing foods and stuff for camping. I I didn't know if the it would be compatible with the finish so I filled a tube partially. Squeezed all the air out and put it in a plastic bin just in case it leaks or eats up the tube. That was about 6 months ago and it's still working perfectly. I think it's time for a full test.
    Mahoney's oil so far has not gelled on me. It just takes too many coats to get the look I want. Most of my bowls are show pieces not users so I prefer either lacquer or one of the wipe on hardening style oils like Minwax wipe on poly or waterlox.
     

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  2. hockenbery

    hockenbery AAW Advisor Staff Member

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    John,

    I have been using plastic water bottles for waterlox but these look like a better solution.

    The plastic bottle need to be squeezed and folded and it takes some fiddling to keep air bubbles out of the folds.
    Also they are making cheaper caps these days.

    Thanks,
    al
     
  3. Jay Fluegel

    Jay Fluegel

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    Wipe on poly is just brushing poly that has been diluted with extra solvent. Why not just add some additional mineral spirits when it starts to get thicker than you like it? I make my own "wipe on" lacquer by mixing brushing lacquer with equal parts of lacquer thinner. With the lathe running at its slowest speed it goes on great and dries to the touch in under a minute.
     
  4. john lucas

    john lucas

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    Yea I thought these would work. I purposely on put a little finish in there because I wanted to have to squeeze as much air as possible out of it to see if it works. It would be a lot easier with a mostly full container. I'm going to let this one sit for another 6 months to see if the plastic deteriorates. Even after that if I start using these I will store them in a plastic bin just in case one does start to leak.
     
  5. robo hippy

    robo hippy

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    A former turner from here used to use the plastic liners from wine boxes. I used to go through the stuff by the gallon, but don't use hardly any of it any more. The curious thing to me is some finishes will go solid in a few months, and others will last a year or three.

    robo hippy
     
  6. Gerald Lawrence

    Gerald Lawrence

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    For Poly the hardening is a chemical reaction catalyzed by oxygen. When it thickens and you thin it you are at risk for a finishing failure. Finish is not cheap, but not worth the risk of a failed finish. If you can exclude oxygen then the finish will last longer. The food tubes sounds like a good idea. There are also accordian like containers which collapse as the volume is lower.
     
  7. Bill Boehme

    Bill Boehme Administrator Staff Member

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    They're not the same thing. Nitrocellulose lacquer is a solvent based finish that cures by evaporation. Polyurethane cures by chemical reaction and once it has reached the point where it is getting thicker, adding a reducer such as mineral spirits or benzine (AKA, VM&P naphtha -- not to be confused with benzene) is pointless because it has already gone "over the hill" and can't be restored to good condition simply by thinning it. The same thing also applies to precatalyzed lacquer and ordinary shellac.
     
  8. Dean Center

    Dean Center

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    This is a very clever repurposing, John. The Coghlan tubes are likely to be the right kind of material, but may be messy in use with finish. There are 'newer' collapsible water bottles used by hikers that would provide another option. Platypus is the best known brand, and they make pint, quart and 2 quart sizes, with either screw lid or push-pull, for $8-$13. I bet they would work. It's also possible to find collapsible water bottles on Ebay, Amazon, or at the dollar store for $1-$2, but with cheap Chinese knock-offs, it's harder to know what they're made of/how solvent resistant they'll be or how leak proof they'll be.

    Thanks for the tip on this vexing problem. I love Lundmark "tung oil" finish and Birchwood-Casey Tru-oil, but they gel so fast it's discouraging. This might be the solution for them.
     
  9. bonsaipeter

    bonsaipeter

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    Preserving Hardening Finishes

    Most of you have discovered that the culprit for the demise of hardening types of finishes is air, or more specifically the oxygen in the air. Thus the above efforts to remove the air from the container in which you are storing the finish. The problem with most containers with a screw on type cap is that they don't seal completely and over time allow for air to enter the container and continually cause the finish to polymerize, AKA harden. A simple solution to this is to store the container up-side-down so that the liquid finish covers the cap which forms a very effective seal against additional air entering the container. Granted, the oxygen which is initially trapped within the container when you close it, will cause some polymerization, but that amount of oxygen is so minimal that the polymerization it causes will not be noticeable. The point is that no additional oxygen can enter the container over time. Therein lies the saving grace.

    CAUTION: WHEN STORING THE CONTAINER OF FINISH UP-SIDE-DOWN, MAKE SURE THE CAP IS SCREWED ON FAIRLY TIGHTLY SO THAT THE LIQUIUD DOES NOT LEAK OUT!!!

    Thanks, Peter Toch
     

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