Mystery blue shade on plane mouth

[Darrenroberts88]

Hi there everyone, I wondered if anyone could help identify this strange blue tone that is starting to form around the mouth of my Stanley NO5 type 11?
it almost looked like the steel is getting hot after use lol but iam sure i don’t plane that fast any way any suggestions would be great. Thanks

 

[Adam W.]

Have you been planing oak ?

 

[Darrenroberts88]

Hi Adam your bang on there. I was flattening a large euro oak table top

 

[Adam W.]

It's the ascetic acid in the timber, it turns steel blue.

Just don't leave your plane on the table, as you'll get a blue blotch on it.

 

[Darrenroberts88]

It's the ascetic acid in the timber, it turns steel blue.

oh that’s a relief thanks. There was a second where I thought hold on have a closed the mouth up to much here and going to cause myself a problem. Haha

 

[JobandKnock]

It's the ascetic acid in the timber, it turns steel blue.

Surely you meant to say tannin

 

[Ttrees]

oh that’s a relief thanks. There was a second where I thought hold on have a closed the mouth up to much here and going to cause myself a problem. Haha

From what you've written, it sounds like you have a tight mouth on this plane.

If you're also setting your cap iron close, i.e 1/32", and have honed a steep leading edge something like 50 degrees,
Then that might be why the bluing is happening.
A tight mouth+cap influence to some extent, makes for far harder work and a lot of heat around the mouth area.

I'm guessing heat greatly helped some sort of chemical reaction of the tannins, since its only around the mouth.

Tom

 

[JobandKnock]

Yes. Normally a tannin blackening would be over almost the entire sole with marks on the iron and cap iron (near the leading edge) and probably some fingerprint size marks on the sides of the plane as well caused by transference of tannin and perspiration/oils from the skin as the plane is used

 

[Adam W.]

Surely you meant to say tannin

No, I meant ascetic acid.

 

[Ttrees]

Can the difference be explained in a sentence or two?

Does it mean the difference between iron rotting (I think I heard a nickname on one of the shipwrights channels)
,and just iron staining.

Or is all iron staining bound to have noticeable detrimental effects on longevity.
I have a load of a super super dense timber that has iron staining all over.
Be nice to know if its good for more than the in-betweens.

 

[Adam W.]

Depends if it's on the surface or from something which has been embedded in the timber.

For example, if you use an angle grinder to cut steel over an oak board, the filings will produce a scattered blue fleck over the surface of the timber. If you brush the filings off straight away, the blue stain can be removed by planing. If the stain has been produced by a steel or iron bolt embedded in the timber for a long period, the stain will be present throughout the depth of the timber along the length of the hole.

The presence of free water increases the amount of blue stain.


A picture of your timber would help.

 

[Adam W.]

FYI.

http://www.vam.ac.uk/content/journa...-04/corrosion-of-metals-associated-with-wood/

 

[WoodchipWilbur]

No, I meant ascetic acid.

... actually, you didn't! I think you meant acetic acid. The sort of stuff you get in vinegar. An ascetic is someone "characterized by severe self-discipline and abstention from all forms of indulgence". I am sure that applies to you too - but I don't think it will mark the bottom of a Stanley NO5 type 11 plane!

 

[Adam W.]

I did, pants at spelling.

And I do mean acetic acid, like what's in that stuff you put on your chips and also eats wire wool. Oak is full of it and kiln dried oak is even more acidic than air dried.

Edit.

Putting wire wool in vinegar also makes a nice blue/black stain for wood.

 

[David C]

There is a reaction between the tannin in the oak and the cast iron of the sole. (I suspect this sole may have flatness issues round the throat).

One also gets this blue black gunge on the chipbreaker.

Fine wire wool and metal polish , like Autosol will deal with the problem.

Sometimes the blue stain gets all over the timber.

A dilute solution of Oxalic acid will clean the timber. Neutralize or wash afterwards.

David Charlesworth

 

[AJB Temple]

And it happens fast. I inadvertently left a Stanley No 4 on some oak beams I was cleaning up under cover outside. Under tarpaulin but rain got on and within 90 minutes I had a blue stain about the size of a spectacle lens.

 

[Adam W.]

From Desch and Dinwoodie. Timber - Structure, Properties, Conversion and Use. 7th. Edition

"...values of pH as low as 3.0 have been recorded in the heartwood of oak.....Because of its acidity, wood can cause corrosion of metals either by direct contact or, in confined spaces, by the emission of corrosive vapour......The principal corroding agent is volatile acetic acid which forms part of the structure of wood constituting 2-5% by mass of the dry wood." Pg. 43

2-5% of the mass of dry wood is a lot.

They go on to say.

" Small quantities of formic and other types of acid are also formed, but their effects can be neglected in comparison with those of acetic acid." Pg. 43

Dinwoodie works at the BRE .

 

[TRITON]

It's the ascetic acid in the timber, it turns steel blue.

Just don't leave your plane on the table, as you'll get a blue blotch on it.

Thats nothing to what a banana skin does.
Discovered boss had left one of his used bananas on the top of a radiator cover in the storeroom.

Black and gunky

 

[Blackswanwood]

Thats nothing to what a banana skin does.
Discovered boss had left one of his used bananas on the top of a radiator cover in the storeroom.

Black and gunky

What had he used it for

 

[Adam W.]

Ugh, blurgh!