Replies

1. 
   highfigh | Dec 11, 2004 04:57am | #1

   It's hard to get these out. If it's not too deep, sometimes it can be sanded or planed out. Otherwise, you need to remove it or use it in the design. The wood fibers are stained. On the good side, you now know how to make a stain for ebonizing oak. Put some steel nails or iron in a container with some warm water. Let it sit and steep for a while and when it's ready for testing, you can wipe or brush it onto a scrap of the oak and it will darken it to whatever level you want. Just practice with it.

   "I cut this piece four times and it's still too short."
2. 
   TomBrown10 | Dec 11, 2004 06:14am | #2

   Mike, I believe the answer is to use oxalic acid. This is one of the ingredients found in many pressure treated deck wood cleaners. Check the bottle to make sure. If anyone thinks my advice is wrong, then please correct me, but I am almost positive it is oxalic acid.

   Oddly enough, I once brought home a new puppy from the pound (as always), and she decided to relieve herself in a neat little puddle on a hardwood oak floor in my house. The floor had an almost 100 year old patina on it, and by the time I got out of the shower and found the mess, the puddle area had been bleached back to the original color of the bare wood at the time it was laid. I was amazed. And, as fate would have it, oxalic acid happens to be an ingredient found in urine as well. Not a good dinner story, but the God's honest truth. Leave it to a love-starved stray to teach me about woodworking...haha. I'll take advice WHEREVER I can get it.

1. 
   GRW | Dec 11, 2004 03:25pm | #3

   I don't how oxalic acid works on this problem but I use oxalic acid provided in crystal form in my non-woodworking job. Just a note of safety for you. Oxalic acid in crystal form can burn the throat and lungs if particles become airborn.  We add water to the crystals ASAP to keep the particles contained. As the oxalic solution starts to dry, and re-crystalize we add more water to keep the crystals contained. We repeat this until the task is completed, and the acid is then rinsed away.

   Good ventalation, a resperator, and keeping the crystals damp is my recomendation.

2. 
   Gretchen | Dec 12, 2004 03:46pm | #7

   the puddle area had been bleached back to the original color of the bare wood at the time it was laid. I was amazed. And, as fate would have it, oxalic acid happens to be an ingredient found in urine as well.

   I can't argue with your story because it happened but our dogs excrete urine that turns oak black.  And that is my story!!!  ;o)Gretchen

1. 
   highfigh | Dec 12, 2004 05:17pm | #8

   What are you feeding them? Seriously, about the only thing I have heard of that turns oak black is iron.
   "I cut this piece four times and it's still too short."

1. 
   Gretchen | Dec 12, 2004 06:06pm | #11

   What are you feeding them?

   Seriously, about the only thing I have heard of that turns oak black is iron.

   And ammonia, which I believe you will find in abundance in urine.

   Gretchen

1. 
   highfigh | Dec 12, 2004 09:27pm | #12

   I know ammonia darkens oak, but I have always seen a brown/grey or green/grey cast to it, depending on whether it's red or white oak. With iron I have only seen kind of a blue/grey down to black, depending on how dark it is. If you handle iron or steel and oak while the wood is wet, green or your hands sweat, your hands will take on a purplish color. If you do it a lot, it gets pretty dark. You can get some good reactions from other people, though.
   "I cut this piece four times and it's still too short."

2. 
   TomBrown10 | Dec 13, 2004 06:28am | #13

   Gretchen, I believe that your experience is due to the fact that, depending on time and temperature, urine of any sort (how did we ever get started on this subject?) will produce ammonia fairly quickly as the products of bacterial metabolism, one of them ammonia, begin to appear. There may also be a component of iron in the urine depending on the dog's diet and individual metabolic activities. If there is a vet out there, maybe they will chime in...lol.

   All I know, is that when my friend, also a woodworker, saw the ferocity of the bleaching process that took place, he began contemplating the possible use of doggie puddles to bleach the floor. Needless to say, we nixed that idea fairly rapidly. I have torn up carpets in houses where dogs lived for years, and found many black-stained wood floors, as any accidents that seeped down through the carpet produced and abundance of ammonia over time.

1. 
   Gretchen | Dec 16, 2004 10:32pm | #16

   All I can tell you is that my dog made a puddle on my oak flooring where most of the finish is worn off. It is black. When our carpets were taken up for floor refinishing there were numerous black spots--I don't think it was from the carpet leaching.   It really makes no difference to me. Gretchen

3. 
   HowardAcheson | Dec 11, 2004 05:59pm | #4

   Oxalic acid is what you want. You can get it at many paint stores and hardware stores. It's also the primary ingredient in "teak cleaner" is you live near a marina.

   Follow the directions on the container and the stains should be gone.Howie.........

   
   

   ---

   Edited 12/12/2004 9:36 am ET by Howie

1. 
   jersey_city_mike | Dec 12, 2004 01:07am | #5

   Thanks to all those who posted. We'll give it a go and report the results.

   mike

1. 
   highfigh | Dec 12, 2004 09:58am | #6

   Is oxalic acid going to work on a stain that's the result of a chemical reaction within the wood? I know it's used as wood bleach, but I don't know if the color of the surrounding wood will be consistant. If it actually does work for this, it'll be a great thing to know. I worked in a lumber yard and we cut a lot of green oak during the summer. I never did find anything that effectively took the color off of my hands after handling the oak, then grabbing the handle of the radial arm saw to cut it. Just had to wear it away.
   "I cut this piece four times and it's still too short."

1. 
   HowardAcheson | Dec 12, 2004 05:42pm | #9

   There are three bleaches used in woodworking. One is chlorine bleach that is used to remove dye stain from wood. A fresh bottle of Clorox or other chlorine laundry bleach will work but a swimming bleach is stonger and faster working. No bleach will remove pigment stain.The second is oxalic acid used to remove water and metal caused stains.The third is what is sold as "A/B" bleach. It is two part and removes the natural color from wood. In other words, you can make walnut and other dark woods cream colored. You can use A/B bleach to remove the green streaks from poplar.Howie.........

1. 
   highfigh | Dec 12, 2004 05:55pm | #10

   Good to know. What is the active ingredient in the A/B bleach? It's sold at paint and home stores? Getting the green out of poplar would make it more useful, I think. As a secondary wood, it's already one of the better ones, but for some things, it could be a primary type.
   "I cut this piece four times and it's still too short."

2. 
   jackplane | Dec 13, 2004 05:08pm | #14

   hydrogen peroxide is the active stuff in two part bleach

4. 
   Liggett | Dec 16, 2004 06:24am | #15

   I've spent many years repairing boats, and any oak parts adjacent to fasteners tend to become black. I've tried oxalic acid, which works somewhat, the 2-part bleaches, which only work a little, and house hold clorox, which doesn't work at all. And low and behold, someone told me about "Whink" Rust Stain Remover, available in grocery stores. This stuff works like a champ! It costs 3 bucks for 6 oz., and the active ingredient is hydrofluoric acid, so be careful. It's made to be used on fabrics and white porcelain, such as toilet bowls. It works best on bare wood, and be sure to rinse thoroughly before finishing. Good luck.