On Sep 16, 6:30*pm, Jules
wrote:
Hmm, so my box of "gold screws" (which I guess are galvanized) say on the
box, "should not be used in treated lumber". Why not? What happens?

cheers

Jules

"Gold" fasteners are usually cadmium plated and not galvanized.
Because they are 'plated' rather than 'dipped", they do not have
enough coating to avoid the corrosive effects of ACQ pressure treated
lumber.

However MCQ pressure treated lumber is now on the market and is
claimed to be much better suited to standard exterior fasteners. As I
understand it, the "M" in MCQ stands for 'micronized" meaning that the
copper compound is much finer and penetrates the wood much better,
therefore they can use less of it. If you look at the wood it only
has a slight hint of green copper color vs the predominant green color
of ACQ. MCQ lumber is sold by Home Depot and "Yella Wood"
distributors. It has a 40yr warranty like ACQ & CCA PT lumber.
KC

On Thu, 17 Sep 2009 12:22:36 -0700, KC wrote:

On Sep 16, 6:30Â*pm, Jules
wrote:
Hmm, so my box of "gold screws" (which I guess are galvanized) say on the
box, "should not be used in treated lumber". Why not? What happens?

cheers

Jules

"Gold" fasteners are usually cadmium plated and not galvanized.
Because they are 'plated' rather than 'dipped", they do not have
enough coating to avoid the corrosive effects of ACQ pressure treated
lumber.

However MCQ pressure treated lumber is now on the market and is
claimed to be much better suited to standard exterior fasteners. As I
understand it, the "M" in MCQ stands for 'micronized" meaning that the
copper compound is much finer and penetrates the wood much better,
therefore they can use less of it. If you look at the wood it only
has a slight hint of green copper color vs the predominant green color
of ACQ. MCQ lumber is sold by Home Depot and "Yella Wood"
distributors. It has a 40yr warranty like ACQ & CCA PT lumber.
KC

Aha. That sounds like the stuff I have; it's certainly a lot less green
than the P-T stuff I remember of a few years ago (enough that I was a
little skeptical about it actually being treated at all when I picked it
up due to the lack of any strong color

According to the end-tags it's branded as MCA - Micronized Copper Azole
(I never realised until now that the tags have a whole bunch of info on
the reverse side - duh).

It still says to use hot-dipped galvanised fasteners, though. That's
interesting because it is indeed the same stuff that Home Depot sells -
yet I couldn't see any hot-dipped screws listed on HD's website (although
I've found that their website's a mine of misinformation before, so who
knows). There's a better supply place in town that I'm sure will do what I
need, but I might swing by HD too just to see what their advice is; it'd
be strange if they sell the wood but not the manufacturers' recommended
fastners!

cheers

Jules

On Sep 17, 3:22*pm, KC wrote:
On Sep 16, 6:30*pm, Jules
wrote:

Hmm, so my box of "gold screws" (which I guess are galvanized) say on the
box, "should not be used in treated lumber". Why not? What happens?

cheers

Jules

"Gold" fasteners are usually cadmium plated and not galvanized.
Because they are 'plated' rather than 'dipped", they do not have
enough coating to avoid the corrosive effects of ACQ pressure treated
lumber.
....more likely zinc plating with a "gold" dichromate rinse.