Teak bungs black marks

[alberto]

Hi,

Some of the repaired bungs show these black stains around the.
Do you know why?
How to remove them?
Thanks

 

[Capt.Bill11]

Are there SS screws under the bungs? Usually the black marks form due to water getting under them and reacting with the SS screw.

Since the discoloration is coming from the bottom up, the only way I have found to remove it in most cases is to remove the bung, change the screw to a bronze one, drill the hole over size to remove the discoloration and rehung it with a larger bung.

 

[Scary]

+1

Are there SS screws under the bungs? Usually the black marks form due to water getting under them and reacting with the SS screw.

Since the discoloration is coming from the bottom up, the only way I have found to remove it in most cases is to remove the bung, change the screw to a bronze one, drill the hole over size to remove the discoloration and rehung it with a larger bung.

You can remove the bungs with a small screw driven through the center of the bung. Pre- drill the bung with a small drill before running the screw. Some guys like to dig out the bung with and awl or 1/4 inch chisel, I find it is really easy to dent the edge of the bung hole this way so the screw method is a safer system. if your brave and good with a drill, you can drill them out with a brad point drill of the same size or slightly smaller. If your careful with the brad point drill you can remove the black stain and glue the new bung in with Tight Bond water proof glue. The green bottle with a duck on it. The tight bond is about the color of natural teak and blends pretty well. A lot of people like using Varnish to glue in bungs, this is fine for varnished surfaces. I install a lot of bungs, I like using Tightbond as it sands off and the glue line is almost invisible. If the stains are really bad of course you can install the next size bung.

 

[alberto]

Thanks,
I am realizing that all with the black stains are the ones that I replaced with ss....

 

[OFB]

Alberto, the black on the teak around the bungs is from water penetration, usually from water ingress through the finish. Its a sign of something needed to be sealed up. You can try and "bleach" the wood back for color but the black is telling of water penetration. Needs to be sealed. IMO. SS is not the issue water is. Take pictures, document and watch cause the wood will rot out, the core will be an issue of not sealed. Again all my opinion.

 

[Xsbank]

I used the small blade of a Swiss Army knife to remove, oh, 10,000 bungs. Well, it felt like that many! Stick the blade down the grain of the plug and just pry it up. No damage to the hole. Usually the bung split in half and was very easy to remove.

Use bronze screws, they are soft and can break easily so pre drill the holes. You might seal the hole with the bung but water penetrates the wood anyway so the fastener may get wet. I used carpenter's glue but many suggest epoxy. Good luck getting out a bung glued in with epoxy!

 

[Capt.Bill11]

Alberto, the black on the teak around the bungs is from water penetration, usually from water ingress through the finish. Its a sign of something needed to be sealed up. You can try and "bleach" the wood back for color but the black is telling of water penetration. Needs to be sealed. IMO. SS is not the issue water is. Take pictures, document and watch cause the wood will rot out, the core will be an issue of not sealed. Again all my opinion.

I believe the plugs he is referring to are in the deck. So there is no finish over them per say. And the black discoloration is coming up the seam between the plug and deck. There is no way to bleach the discoloration out since it goes all the way down into or up along the seam. So you can bleach the surface all you want but the stain will still be there or just come back.

 

[Larry M]

...glue the new bung in with Tight Bond water proof glue. The green bottle with a duck on it. The tight bond is about the color of natural teak and blends pretty well. A lot of people like using Varnish to glue in bungs, this is fine for varnished surfaces. I install a lot of bungs, I like using Tightbond as it sands off and the glue line is almost invisible. If the stains are really bad of course you can install the next size bung.

I like the Tight Bond idea alot. I've always used epoxy for exterior or varnish for interior work on bungs. The epoxy is hard to clean up around the plugs unless I'm replacing planks and sanding. I've also found the epoxy leaves a dark glue line between the plank and bung over time as it ages.

 

[OFB]

I believe the plugs he is referring to are in the deck. So there is no finish over them per say. And the black discoloration is coming up the seam between the plug and deck. There is no way to bleach the discoloration out since it goes all the way down into or up along the seam. So you can bleach the surface all you want but the stain will still be there or just come back.

Capt Bill

My point really is that its water getting to the fasteners that's the issue. Not that the fasteners are stainless. The finish is natural teak on the decks including the bungs. The black is caused by water getting in under the bung, under that teak finish. But ya my written word is not so grand. Sorry.

 

[alberto]

Thanks again,
What I did really was to subsitute brass fasteners by ss fasteners after re-drilling to gain space for the bungs.
Maybe the point is that I used carpenter white glue, which is enough for retention but obviously not for sealing.
I will do some testing, as this is an interesting subject, (still many bungs to replace...)

 

[Capt.Bill11]

Capt Bill

My point really is that its water getting to the fasteners that's the issue. Not that the fasteners are stainless. The finish is natural teak on the decks including the bungs. The black is caused by water getting in under the bung, under that teak finish. But ya my written word is not so grand. Sorry.

I see what you mean now. Yes water is the issue. But I've only seen the black rings form around bungs that are covering SS screws. I don't think I've ever seen them form around bungs over bronze screws.

 

[boatpoker]

Stainless steel corrodes with the absence of oxygen. Water weeps through the wood and becomes stagnant. Stagnant water is simply de-oxygenated water. Stainless steel is inappropriate for this purpose, better off with bronze.