Cypress depression

[Dhankx]

I had made several chairs in cedar and never had a problem. Then I made a chair for my wife in Cypress because the wood store was low on choices for cedar.  Originally I was very happy with working with it.  It only took a month or so and this black/blue dots and smears started showing up.  I assume it's mold but don't know.  Does anyone know if : #1 is this normal for cypress?  #2 will it perhaps go away on its own in the sun maybe during the summer #3 if not, what's a good approach to get this cleaned off and resealed?  I originally sealed it with cedar seal - which I used on cedar.  Seems to work OK and figured it would work ok on this.  Original and molded pictures attached.  thank you for your help folks.

[Coop]

I have had the same problem and don’t think it has anything to do with being the cypress although mine is made of it as well. Mine showed up as the finish began to breakdown and I suspect mine being under a large shade tree and not getting sun probably had a lot to do with it. How long has your finish been on there? 

[Dhankx]

I put on 2 coats about a day apart then let it sit for about 5 days.  Then sat it outside, it's been outside about 6 weeks.  It's sitting right beside a cedar chair with the same stuff on it (but only 1 coat!) that has no similar problems.

[Coop]

Mine has been out about a year and a half so I suspect your problem was there prior to finishing. Not that the finish has anything to do with it but what did you use. If it were me, I would wait a while to see if it shows up on other parts of the chair. If not, remove the finish on the problem areas and treat the wood with TSP to remove the mold/mildew, rinse completely and re-finish. 

[Chestnut]

This really looks like all of the mold is contained within the sap wood. What i think is happening is the heartwood is durable and the sapwood is starting to rot away. The difference with the cedar is that it probably doesn't contain any sapwood. IIRC cypress and cedar are closely related.

Just a guess.

[Tom King]

It's definitely in the sapwood on the arms, but it's a long ways from rotting.  Most likely, the wood was not completely dry when you bought it, or the sapwood soaked up some moisture somewhere from the source, to the chair.  It's trapped under the finish, and the mold/mildew spores were already there.

I use a lot of Cypress, but am not any help here.  I either paint it, or leave it bare, and don't use any sapwood, or at least try not to.

[Tpt life]

A few thoughts...

Some woods will mineral stain, and the mineral Wil oxidize over time. The finish might even promote the oxidation.

Molds and mildews live off of biological tissue. To remove it, you’d have to remove the finish, completely neutralize the mold/mildew, then refinish. 

First scenario, you will never remediate. Second scenario would take forever, and be ineffective if you were wrong about it being biological. 

There is a slight chance the contamination is in the finish itself. I don’t know Cedar Seal and would have to read up. In that scenario you’d still need to strip and refinish to remove it. 

All that to say: How attached are you to the chair? If you like building things, it might leave you happier to build another chair.  

[Dhankx]

2 hours ago, Tpt life said:

A few thoughts...

Some woods will mineral stain, and the mineral Wil oxidize over time. The finish might even promote the oxidation.

Molds and mildews live off of biological tissue. To remove it, you’d have to remove the finish, completely neutralize the mold/mildew, then refinish. 

First scenario, you will never remediate. Second scenario would take forever, and be ineffective if you were wrong about it being biological. 

There is a slight chance the contamination is in the finish itself. I don’t know Cedar Seal and would have to read up. In that scenario you’d still need to strip and refinish to remove it. 

All that to say: How attached are you to the chair? If you like building things, it might leave you happier to build another chair.  

Great feedback all.  Yes I don't mind building another chair, my main conflict at this point is if I ever use Cypress again.  I was originally excited when I found out it was a LOT cheaper than Cedar.  Then I found out the southeast, cypress is king - NW cedar is king. So I had high hopes I would be able to continue doing outdoor stuff with cypress. Moisture did sit on this chair for a long time when it snowed here a bunch - but we only get 2-3 snows per year and like I said nothing similar happened with the cedar.  As far as the wood not being dry: From the point I got it from the wood place to the point it was actually put outside I'd guess it was 4 months. I don't build things very fast.  Something about the sap wood is definitely a factor. I think I'll find a scrap piece with sap wood and just sit it outside untreated and see if it does the same thing.  I did search the internet on this and found only 1 instance of it being talked about . With that guy and that thread the seemed to conclude it was just a cypress thing.  Kind of disheartening.  

[AceHoleInOne]

If this were me, scrub brush, bucket of TSP and household bleach or deck cleaner. First, wet the wood good with water then scrub with the solution and hose off really good. If you still see the mold use straight house hold bleach and a 1 gallon weed sprayer with some water. Let sit on wood a few min and scrub chair, rinse with hose really good.

Think of it like cleaning your wood deck at home.

Maybe find a better top coat containing an oil, they seem to last longer than water-based outdoor finishes. From time to time wash your chairs with soap and water to keep the dirt off.

 

-Ace-