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Regarding wood bleach

Discussion in 'Wood and Canvas' started by ddewees, Feb 5, 2008.

  1. ddewees

    ddewees Woodworker

    Yesterday I took advantage of a (relatively) warm Vermont day and Citristrip-ed the inside of a canoe in the shop then took it outside for the hot-water-from-the-garden-hose treatment. I then realized that the inside was going to need bleach, and I didn't have anything on hand. Over the years I've tried a variety of Home Depot-type wood brighteners, as well as a two-part teak cleaner. This morning I went back to this forum and searched past threads for ideas about what works best, and decided to order up some Snappy Teak-Nu from Jamestown (thank you Michael). I had tried Te Ka teak cleaner in the past and liked it, but it seemed pretty pricey, as is the Snappy product. Then I noticed that the order confirmation listed the stuff as "sodium hydroxide". So apparently what this $20 kit contains is probably less than $1.00 worth of lye solution (dry sodium hydroxide flakes or pellets can be purchased over the net for $5/pound, which probably translates to about 10 cents a quart of solution).
    Part B is undoubtedly a relatively weak acid to neutralize the basic sodium hydroxide after it has done its work. Why doesn't one of our scientist forum members do a little analysis and experimentation, and make the result available to all of us, or at least tell me why I'm wrong? Do you think there is really a secret ingredient in these products, or should a kid with a chemistry set be able to reproduce them for next to nothing? I'm for the "open source" approach.
    Don in Vermont
     
  2. bob goeckel

    bob goeckel Wooden Canoe Maniac

    hey don, you might try posting this on the woodenboat website. i know they have some chemists there. and probably alot more viewers.
     
  3. mark wismer

    mark wismer WCHA Member

    drain cleaner & vinegar.
     
  4. bob goeckel

    bob goeckel Wooden Canoe Maniac

    he wasn't asking about laxatives mark!:eek:
     
  5. OP
    OP
    ddewees

    ddewees Woodworker

    No Drano

    I read up on Drano. It has NaOH, but also aluminum chips with which it reacts violently and makes a lot of heat when it hits the water. Not in my canoe! Maybe I will see what the WoodenBoat crew has to say (not that a lot of you folks aren't that crew, too.) Thanks.
    Don
     
  6. David McDaniel

    David McDaniel Canoe Dude

    Drano

    I have had good luck just using deck cleaner after stripping.
    The one that I use contains oxlasic acid, which is a mild acid.
    Then rinse well with water.

    later Dave
     
  7. Michael Grace

    Michael Grace Lifetime Member

    Don, you are correct that wood cleaning/bleaching solutionsare all fairly simple and the ingredients can be very inexpensive. However, these products may have a variety of other ingredients in small amounts (it is unclear to me how important these other ingredients are to the functional properties of the bleach systems), but the main active ingredients for several products are (all in water):

    Te-Ka
    Part A: 5-10% sodium hydroxide
    Part B: 20-30% phosphoric acid


    Snappy Teak-Nu
    Part 1: 7% sodium hydroxide
    Part 2: 7% hydrochloric acid


    Star-Brite Teak Cleaner, Brightener
    Cleaner: 5-10% sodium hypochlorite (active ingredient in household bleach)
    Brightener: 4-10% oxalic acid


    Some one-part cleaners contain either citric acid or oxalic acid or other chemicals. They generally are very weak bleaches. Oxalic acid removes iron stains especially from tannin-containing woods. Tannic acid, iron and water react to produce a black product, and tannins are especially rich in certain woods like cherry and white oak. Thus, boats containing white oak fastened with iron show black stains. Oxalic acid will remove these stains, but it has little effect on other wood species- wood that is darkened because of other reasons. I recently restored an old WWII-era Thompson skiff that had white oak open gunwales fastened through the ribs with steel screws. The pure black stains around every screw were completely removed by treatment with a saturated solution of oxalic acid.

    Oxidizing bleaches change the molecular structure of chromophores (color-producing chemicals), and therefore work well on a variety of woods, removing even the natural color of the wood. Thus, these are generally not suitable for restoration work unless you wish to change the color of the wood by bleaching and re-staining. 2-part bleaches sold in home centers and woodworking shops may be the oxidizing type. Parks brand, for example, has the user applying sodium hydroxide and hydrogen peroxide. Together, these oxidize and therefore alter the natural color of the wood.

    The two-part bleaches Snappy Teak-Nu and Te-Ka work well on a variety of types of wood commonly used in boatbuilding. These two-part systems generally are not strong oxidizers, so they don’t dramatically alter the natural color of the wood. This is why their manufacturers call them "teak cleaner" and not "bleach". On the other hand, there are two-part systems that when mixed become strong oxidizers. If you’ve ever seen an old boat treated with an oxidizing bleach, you know how un-naturally light the wood looks. Aged red and white cedar (planking and ribs, respectively) can become uniformly pale in color; all hint of aged patina can easily be lost. This is what many people imagine when they think “bleach” (laundry bleach is an oxidizer that works especially well on cotton, making it very white). Products like Teak-Nu and Te-Ka are not bleaches in this sense, and they leave natural color in the wood.

    One thing to note with products like Te-Ka and Teak-Nu: the “part 1” is sodium hydroxide, and bases such as this darken wood considerably. Thus, order is important- base first, acid second. The acid neutralizes the base, removing the dark tone imparted by the first step.

    Michael
     
  8. OP
    OP
    ddewees

    ddewees Woodworker

    Thank you Michael. (I was hoping you would reply, knowing that you've used a lot of these products and have a chemistry background.) As I said, UPS should be delivering the Snappy Teak-Nu today for the current project, but I'm tempted to experiment with homemade solutions of NaOH and HCL, which are readily available and dirt cheap. I'll report back here if anything comes of it.

    Meanwhile in Googling wood bleach I find reference to sodium percarbonate bleaches (as in Oxy-Clean and all its miracle-working clones that have appeared in recent years). Some less-hyped and more concentrated brands of deck cleaner with this as the primary ingredient (such as Natural Choices Oxy-Boost) make all sorts of claims about being ideal for cedar, not removing natural color, and being environmentally benign. The powdered reagent is also available cheap in quantity. Does anyone have experience with this variety of bleach/cleaner?

    Thanks everyone for contributions. This whole business of stripping and cleaning the insides of old boats is by far the messiest, most unpleasant part of the refurbishing process, but one that makes a huge difference in the looks of the completed project. Next to the usual suggestion of getting someone else to do it, finding cheap, straightforward methods and materials seems to be the way to go. Thanks for the information and ideas.
    Don
     
  9. Gary Willoughby

    Gary Willoughby Boat Builder

    Years ago Guy Cyr gave me a recipe for paint remover using Drano (it works quite well) You must add the Drano to cold water and use a metal pail. But I still had to use bleach so I don't think drano could be used as a bleach.
     

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