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Black Staining on Vanished Boards

Black Staining on Vanished Boards

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Stef Hogan30/11/2015 20:58:11
3 forum posts

Hi, In my spare time I make "Hand Carved Signs" House Names, Stable Plates etc. For the board I have been using Kiln Dried 20-25 mm. Thick American White Oak finishing with 3 coats of Ronseal exterior wood varnish. After a period of about a year I'm finding that the vanish seems to degrade and a sort of "Black Staining" appears making the sign look Old and Spoiled.

I wonder if a coating of a "shellac" based product like Pale Polish before vanishing might do the trick or is it the wood? I have been casually advised the using European or English Oak would be better being less susceptible to moisture and fungal problems.

Any help or advice would be appreciated

Stef

Steven02/12/2015 15:19:04
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143 forum posts
11 photos
367 articles

Hi Stef,

Maybe a picture or two would be helpful, there could be a couple of reasons for this happening, ferrous metals reacting with the tannins in the oak would cause staining, this could be from fixings or contamination in the workshop, remnants of wire wool for instance.

From your description the most likely cause is a UV reaction, so a finish with high UV protection would be needed I don’t know enough to advise on this, perhaps someone else will be able to help.

American White Oak should be fine outdoors, it’s Red Oak that isn’t so good and European Oak is still prone to staining.

Hope this helps a little, Steve

Stef Hogan02/12/2015 22:53:23
3 forum posts

Hi Steve, I appreciate your input and tend to agree with your thoughts. I have a couple of pictures and will try and attach them

Sorry no luck

Steven03/12/2015 17:00:45
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Moderator
143 forum posts
11 photos
367 articles

Hi Stef,

Here is a **LINK** to instructions for uploading your photos.

Steve

Stef Hogan03/12/2015 22:38:32
3 forum posts

Thanks for that Steve, unfortunately all I got was :

ERROR

this article cannot be found.

But, I have done further investigations and I'm 90% convinced it's as you suggested, UV damage. The signs, a cluster of 5, are set in a South facing hedge, when I checked the back there were no hint of any damage.

At the moment I'm thinking of Not Varnishing (I can't find UV protection Varnish) but using a UV protective Oil which I have found, I'm also considering prior to the Oil, a couple of coats of Pale Polish ( a Shellac based product) in the hope that it will inhibit any mold growth.

Any thoughts you have will greatly appreciated.

Cheers Stef

Steven11/12/2015 19:27:52
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Moderator
143 forum posts
11 photos
367 articles

Hello again Stef,

Did you manage to create an album and upload your pictures? If so it sounds as though you are trying to add pictures to your original post, it will work if you add them to a new posting.

Are you looking at Osmo UV protection oil by any chance? I’ve not used it but the reviews seem good, it claims to have a UV factor 12, I guess we will have to wait for some time to find out. I’m a little concerned about using shellac based pale polish outdoors, it may be that as a sealer its fine but check that it works with the oil first.

Steve

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