green spots on timber

[Johno1]

Hello, I recently purchased larch tounge and groove timber that has started to get covered in green spots ( please see images attached). I was going to use this timber for a garage door but am now unsure how it will turn out.

 

Does someone know what this is called?

 

Can this timber be stained?

[Daniël Bos]

Looks like mould to me?

Possibly the timber was not dry when it was cut into T&C? Or the storage afterwards has allowed it to get too wet.

If you make sure the timber is dry and it'll stop growing and you'll be able to sand (most of) it off.

[daltontrees]

Yep that's just mould. Dry the wood and wipe it off with meths then sand if necessary. Larch is famously decay resistant and is used externally on buildings unstained as it will eventually 'silver' and a take on a distinctive and some say desirable natural weathering colour.

Options are to use a clear fungicidal preservative, a clear ,matt varnish or a combined stain/preservative. Or do nothing, the mould would get washed off outdoors.

[agg221]

The mould, otherwise known as blue stain, is likely to go quite deep. You could try sanding it but if it won't go within an acceptable depth then either letting it all go silver or applying a dark woodstain or paint are your best options. It doesn't have any structural significance though and mould or greying is pretty much inevitable on unpainted or unvarnished timber used outside.

 

Alec

[Johno1]

Thanks a lot for your replies. It looks like I will be spending money on this timber. I got a moisture content (MC) reading done on it and it was showing 25% MC. The supplier has agreed to take it back so this might be the best thing. I should probably wait until spring or summer before I get replacment timber.

 

I just wonder if anyone knows how good Larch timber is? I got a fencing job done on the farm this summer and I was supplied ( and charged plenty) with larch strainers & intermediate posts. The contarctor told me that Larch was a good hardwood. But I recently read that Larch is a hard Softwood.

 

Anyone got experience with Larch?

[agg221]

Larch is a softwood. It's reasonably durable outside, but that's the heartwood, not the sapwood. It is reasonably strong and hard, and has long grain so it tends to move a bit - a bit like oak or sweet chestnut. It was used for pit props and miners trusted it, so it's pretty reasonable for strength and durability.

 

Alec