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Forum topic by JerryLH posted 11-04-2017 12:53 AM 706 views 0 times favorited 14 replies Add to Favorites Watch
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JerryLH

132 posts in 1150 days


11-04-2017 12:53 AM

Topic tags/keywords: question mahogany plane milling sanding shaping chemical reaction imprint stain

I recently acquired a pickup load of pallet tops and bottoms which were made from 1X mahogany (not the 2X cross stringers). This mahogany has been in the barn, nails pulled and stacked fairly straight for over well over 30 years. It was/is rough – of course I cleaned up a couple of pieces to see what it would look like. So far nice but nothing great (only those 2 pieces so far). Here’s the question – after I planed up those 2 pieces I left them laying out on my island work area which includes two cast iron saw tops. Where the mahogany lay across the saw tops – the near perfect imprint of the boards were created on the saw tops (like a heavy fog on the otherwise shiny saw tops). The foggish imprint was not removable by cleaner of any type. Removal of the imprints required abrasives. Is this common to mahogany?

Regards, Jerry

-- Develop your character -- for it becomes your destiny. Jerry - Mannford, Ok


14 replies so far

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tomsteve

667 posts in 1058 days


#1 posted 11-04-2017 12:39 PM

sometimes when i leave a piece of red oak on my TS i get the same.

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Carloz

981 posts in 430 days


#2 posted 11-04-2017 01:38 PM

I think someone sold you a bunch of red oak for the price of mahogany :-)

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JerryLH

132 posts in 1150 days


#3 posted 11-04-2017 03:57 PM

No – I appreciate the thought – but it is mahogany – and as to cost – $95.00 for my 3/4 ton long bed pickup loaded to the rails – he wasn’t getting rich – and finally, ‘he’ is a long time acquaintance (an ex but friendly brother in law). My concern about the chemical reaction between the wood and the metal top was – I planned on using this wood for small toy chest, etc and I just wanted to insure the wood to be the cause (of the imprint) and not some chemical that ‘might’ be ‘in’ the wood. If it’s just outgassing of the wood – right after fresh wood being exposed to the atmosphere I wouldn’t be concerned. I ‘always’ appreciate ya’lls thoughts – Thanks.

-- Develop your character -- for it becomes your destiny. Jerry - Mannford, Ok

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TungOil

747 posts in 333 days


#4 posted 11-05-2017 01:01 AM

I had this happen with some douglas fir. Cut it and let it sit on the TS overnight and it left a perfect image of the wood, knots and all. I attributed it to the moisture in the doug fir, but your experience makes me question that theory. I also had to use abrasives to remove it completely.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

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Lazyman

1506 posts in 1226 days


#5 posted 11-05-2017 02:50 AM

The tannin in many woods (especially oaks but many others as well) will react with moisture and iron. You’ve probably seen this many times with black stains where iron nails are driven into a fence or siding. I’ve used this reaction to ebonize wood and it only takes a few minutes for the reaction to occur. A little bit of moisture in the wood or a slight condensation on the iron will very likely cause staining to occur in high tannin woods. I just did a quick search and mahogany is one of the high tannin woods that can be easily ebonized so my theory is that is what’s happening here.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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JerryLH

132 posts in 1150 days


#6 posted 11-05-2017 03:10 AM



The tannin in many woods (especially oaks but many others as well) will react with moisture and iron. You ve probably seen this many times with black stains where iron nails on are driven into a fence or siding. I ve used this reaction to ebonize wood and it only takes a few minutes for the reaction to occur. A little bit of moisture in the wood or a slight condensation on the iron will very likely cause staining to occur in high tannin woods. I just did a quick search and mahogany is one of the high tannin woods that can be easily ebonized so my theory is that is what s happening here.

- Lazyman

Thanks a ‘Lot’ Lazyman – that really makes me feel more comfortable using this wood in close contact with folks (especially little ones). I appreciate the feedback! FYI – My thought as to lazy—If I needed to hire an employee – I would look for a lazy perfectionist.

Regards, Jerry

-- Develop your character -- for it becomes your destiny. Jerry - Mannford, Ok

View Aj2's profile

Aj2

1178 posts in 1636 days


#7 posted 11-05-2017 03:21 AM

I don’t dispute what you wrote Lazyman. Jerrys post is nothing what I’ve experienced with mahogany.Ive left scraps and assorted pieces laying out on my tablesaw and jointer beds and never had any stains left behind.
I am really curious to see what the Boards look like.
I guess it could happen if there was a very high dew point.

-- Aj

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Lazyman

1506 posts in 1226 days


#8 posted 11-05-2017 12:40 PM

I too am curious what it the problem looks like. If the wood has been in a barn, it could still have a fairly high moisture content depending upon the environment. Right after planing it, the newly exposed wood could be more moist than the removed surface wood. A moisture meter would be helpful to see just how high the moisture content is, especially the newly exposed wood.

To be totally comfortable, especially with little ones, you could conduct a little test by making the wood a little wetter and then putting a piece of iron on it, an old chisel or plane iron would do ,to see if the reaction is even more noticeable. A control might be to put a piece of stainless on it as well to make sure that it doesn’t turn there.

I’m retired now, but my Lazyman moniker and tagline is based upon my own experience as a I/T guy hiring people and building project teams. My experience is that people that are a little bit lazy, but otherwise competent, come up with the best, most innovative ideas. The key is to find just the right amount of lazy. This sometimes drove some of my colleagues crazy but being a bit lazy myself, I knew how to not only tolerate the good ones but how to use them effectively to build better systems. My projects usually came in ahead of schedule and under budget so no one could complain about my team of lazy too much.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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JerryLH

132 posts in 1150 days


#9 posted 11-05-2017 02:14 PM



I don t dispute what you wrote Lazyman. Jerrys post is nothing what I ve experienced with mahogany.Ive left scraps and assorted pieces laying out on my tablesaw and jointer beds and never had any stains left behind.
I am really curious to see what the Boards look like.
I guess it could happen if there was a very high dew point.

- Aj2

Thanks for the feedback Aj2. I’ll try and take some pics of the wood and recreate the shadow imprints after getting back from Church today—once that’s done I’ll post some pics. Thanks to all for the feedback.

Retired & Regards, Jerry

-- Develop your character -- for it becomes your destiny. Jerry - Mannford, Ok

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JerryLH

132 posts in 1150 days


#10 posted 11-05-2017 09:13 PM

Here are some pics of the wood and the fog imprint. I didn’t leave the wood on the TS as long this time and the imprint is not as perfect as when the wood was in contact with the TS longer. This imprint was created in just 3 – 4 hours.

-- Develop your character -- for it becomes your destiny. Jerry - Mannford, Ok

View Lazyman's profile

Lazyman

1506 posts in 1226 days


#11 posted 11-06-2017 01:12 AM

I think that the mahogany has a high moisture content and is basically rusting the table. Planing the wood is allowing the moisture to escape more easily. Did those small black splotch at top center of the wood picture appear afterwards? That is exactly what I would expect with ebonizing using iron to react with the tannin (though I have not ebonized mahogany before).

If you have a moisture meter, test it. Another relatively quick way to calculate if it is has a high MC without a meter is to weigh a cutoff that will fit in a microwave oven and then heat the cutoff for about 2 minutes on 50% power (longer for larger pieces of wood). The piece should get pretty warm but be careful not to overcook it to the point it starts to char. Let the wood cool off and weigh it again. You need a scale such as a kitchen scale that will measure grams or 8ths of an oz. If it loses weight, it is giving off moisture. Repeat this until it stops losing weight or you can just stop when convinced it is losing a lot of moisture. If you continue until it stops losing weight, you can calculate the percentage of moisture the chunk lost during the process to approximate the current moisture content. This is actually fairly similar to how moisture is scientifically determined except they use an oven and heat it for 48 hours at 100 degrees to calculate the moisture content.

BTW, I have a shop microwave I bought at a garage sale for $7 that I use for drying green bowls so I don’t have to worry about messing up my microwave. You might want to use a covered pyrex dish to contain anything that might get you in trouble with your better half. Just take it out of the dish to cool.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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JerryLH

132 posts in 1150 days


#12 posted 11-06-2017 04:12 AM

Thanks Nathan. If the imprint is moisture related and form of rust – it would seem that Vinegar, lime-away or CLR (Calcium Lime Rust Remover) would remove the imprint if it is rust. I believe I tried CLR but I’m not sure – I’ll try again tomorrow. To be honest I was going for the tannin effect and still think it to be a strong contender here. If it were a moisture reaction I should be able to take a piece of wood known to be holding as much or more moisture than the mahogany and get the same foggy Imprint.
The weather is changing here in Oklahoma this week & I’ll the different wood a test run tomorrow.

Thanks for the feedback & short chat. Regards, Jerry

-- Develop your character -- for it becomes your destiny. Jerry - Mannford, Ok

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Lazyman

1506 posts in 1226 days


#13 posted 11-06-2017 01:12 PM

The tannin effect requires moisture so I don’t think it would occur if there wasn’t sufficient moisture in the wood to react. It might actually be iron oxide that reacts with the tannin so a little iron probably has to be converted to rust before it reacts with the tannin. If those little black splotches on the wood show up after laying on the table, to me that is a pretty good indicator moisture being the primary culprit so determining where the woods moisture content is might help narrow it down.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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JerryLH

132 posts in 1150 days


#14 posted 11-07-2017 01:05 AM

Ok – I placed green (non mahogany) on my TS, I placed a wet rag on TS – none made the imprints but the mahogany. I placed a piece of the mahogany on the TS that had not been planed and had a slight cup to the board – I turned the cup up so only the edges of the board were in contact with the TS. This piece left the imprints along both edges that were in contact with the TS. That’s all I know – think I’ll just make some sawdust.

Thanks to all for the informative feedback.

Regards, Jerry

-- Develop your character -- for it becomes your destiny. Jerry - Mannford, Ok

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