Problem using Cypress as Outdoor Furniture

[Mike Minto]

I have built some chairs, benches and a table for outdoor use from Cypress. After some time in the weather, black stains and streaks have begun to show up, and grow alarmingly large, making the furniture VERY ugly. Anyone else have this problem? What is it? Is there a cure, short of painting the furniture - which I have started to do. Will this painting cause more problems by sealing the wood's pores? Some of the wood with the stains has been treated with Thompson's, some not. HELP! :) Mike

[Peter Quadarella]

Black stains can be caused on that type of wood from contact with many types of metal. For example, using galvanized screws will cause black stains. Even just leaving some metal stuff on top of them can sometimes cause the stains. it has something to do with the acids in the wood. Usually, I am sure to use stainless steel screws on these types of woods (stainless steel does not cause the stains).

[Chris Padilla]

Mike,

Do you have any pictures of the stains? Normally, it is as Peter described. Do the stains appear to emanate from screws or any type of metal used in the furniture construction?

[Mike Minto]

thanks for the replies, but there is no metal contact with the wood other than the stainless steel screws i used to put them together. i'll get some photos soon and post. mike:D

[Greg Hines, MD]

I have built some chairs, benches and a table for outdoor use from Cypress. After some time in the weather, black stains and streaks have begun to show up, and grow alarmingly large, making the furniture VERY ugly. Anyone else have this problem? What is it? Is there a cure, short of painting the furniture - which I have started to do. Will this painting cause more problems by sealing the wood's pores? Some of the wood with the stains has been treated with Thompson's, some not. HELP! :) Mike

That is most likely due to the fasteners that you used. Stainless steel would not discolor it like that, but galvanized nails or screws will. I do not think that there is anything you can do short of painting over it with Kilz or some similar agent.

Doc

[Greg Narozniak]

When I built my A chairs I used Galvenized brads and nails and the "coated" deck screws and i never got any 'staining". I would go the mcFeely's route as others have said.

[Dick Sylvan]

Sounds to me like it could be mildew or some type of fungus. A fairly weak solution of bleach will kill the mildew, so you might try it on a small area as a test.