Re: oxalic acid

True, oxalic acid is not a chemical oxidizer and perhaps the term "bleach/bleaching" was too general but it is common to boatyards and woodshops and usually refers to removing discoloration from the wood. "Oxalic acid is referred to as a "reducing bleach.  There are three general classifications of chemical bleaches used on wood: oxygen bleaches, chlorine bleaches and oxalic acid."  WoodenBoat, Nov/Dec 2002, pp. 28 & 29.    An example of oxygen bleach is a solution made from sodium hydroxide and 30% hydrogen peroxide.  Sodium percarbonate solution is another oxygen bleach.  An example of a chlorine bleach is a dilute solution of sodium hypochlorite (Clorox).  Strong chlorine bleaches may be made from calcium hypochlorite.  This is the bleached used in swimming pools. 
 
Oxygen based bleaches will remove stains caused by mildew and grayish residue caused by the action of sunlight on wood but will leave the natural color of wood intact.  The best use of chlorine bleach is to kill and remove fungal and microbial stains.
 
"Oxalic acid is also used to lighten the graying effects of outdoor exposure.  it is the ingredient in most deck 'brighteners,' but phosphoric acid can be used for this purposed as well.  Used on wood that has been stripped for refinishing, it will lighten the color and reestablish an even tone, particularly for cedar, teak, spruce, and mahogany.  Spars often have dark discolorations, and oxalic acid can help to eliminate them after stripping and before revarnishing.  If properly neutralized and thoroughly rinsed with distilled water after use, oxalic acid does no damage to the wood." Woodenboat, Nov/Dec 2002, p. 28 - Using Wood Bleach by Jeff Jewitt.
 
The cost of 1 gallon of Dekswood is about $11.00 without tax and includes the water, container, directions and warning.
 
The article from the Nov/Dec issue of Woodenboat is an excellent reference on the use of bleaches and oxalic acid. 
----- Original Message -----
From: ngatewd
Sent: Thursday, May 15, 2003 6:04 PM
Subject: [bcc] oxalic acid

Oxalic acid does not bleach the wood, rather it facilitates removal
of "dead" wood fibers.  An inexpensive source of oxalic acid is your
pharmacy.  They can special order oxalic acid crystals for a lot less
than a hardware store sell a product that simply contain oxalic acid.
Ned

----- Original Message -----
From: “ngatewd” <ngatewd@ksu.edu >
To: <bcc@yahoogroups.com >
Sent: Thursday, May 15, 2003 3:04 PM
Subject: [bcc] oxalic acid

Oxalic acid does not bleach the wood, rather it facilitates removal
of “dead” wood fibers. An inexpensive source of oxalic acid is your
pharmacy. They can special order oxalic acid crystals for a lot less
than a hardware store sell a product that simply contain oxalic acid.
Ned

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Oxalic acid does not bleach the wood, rather it facilitates removal
of “dead” wood fibers. An inexpensive source of oxalic acid is your
pharmacy. They can special order oxalic acid crystals for a lot less
than a hardware store sell a product that simply contain oxalic acid.
Ned