Dissolving slate?

Anyone ever seen this? I know slate can be problematic as an exterior cladding. This home was right on the beach. Wall is east-facing (opposite the beach). The round holes were filled with a substance that can be best described as ashes, that you might find in your fireplace. Very soft, dusty, but no smell. Area surveyed was to the left of the ladder in the first pic. Moisture was elevated in the wall near the holes, but no idea if this is cause or effect.

Looks like rust also.
Something attached previously or behind the wall would be my first thought.

Are you sure slate,could it be terra cotta?

Thanks Bob for the response. Yes, it was slate. What would the rust be attacking? Sure, there is a certain amount of iron in slate giving it it’s red and yellow color. I have learned that slate also has a fair amount of carbon in it, and this would be more indicative of what I saw (almost like powdered pencil lead).

In the past I had that type tile and made the mistake when very young of thinking I could clean it with Muraic acid yet never had any deterioration of material.

Something must have been drilled or mechanically attached somehow for some reason .
Could that not be rusted lathing behind it and the ground material be what was left from grinding/drilling?

Kind of an odd pattern from drilling, don’t you think? Looks like a reaction of sorts to me. I know a bit further south down the coast, I did an inspection many years ago at a condo complex that had slate cladding that caused all sorts of moisture related problems. It was only a few years old and the builder ended up removing and replacing all of it.

Never see the slate wall covering here but see it on floors and not sure it is much different yet none the less pretty sure rust is from some other component.
Bad flag pole mounting or dish perhaps at one time ?

Looking forward to others comments to learn something maybe.

hope no hidden moisture related issues at lath that could seep through and effect slate.
Can’t imagine that.

Yes, and thanks again Bob for your insight. Maybe others here will have different ideas.

I wonder if it was cleaned using an acid and it was not washed off all the way in that area. I cleaned a marble top years ago with muratic acid and did not get it all off and it made similar marks to what you have here. Just a thought.

It certainly LOOKS like acid. Possibility I suppose. Thanks Greg for your response.

ask Frank Albert!

frank albert <Frank@albertsroofing.com>;

That is acid drips from the tinsmith soldering copper or galvanised.
Do you see any coper or solder work?
There are typically 3 types of slate.
The are graded like any other material.
The cheep slate has a life of up to 35 years.
Been some time but I will get some reference material if you need it.
Been ten years sense I respired or laid slate.
Dam maybe more for roofing with the material…

I’ve seen similar places on Vermont and Penn slates. Penn were the worst. There can be iron deposits in slate and they’re brownish in color to start. Then, they rust through.

I can’t find the revelant pix I want. Here are some soft Vermonts. These holes came from the nails below though they weren’t sitting up very much.

Soft Vermont Slate (3).JPG

Soft Vermont Slate (5).JPG

Soft Vermont Slate (7).JPG

Frank fasteners also have qualities that can effect slate and its degrading processes.
In your second photo the fasteners seems to be suspect in the condition of the slate. Look at there location.
Look where the holes are located . In the other photos it looks like poor quality slate and galvanized nails do leave degrading signs that are not so well analysed to the novice.
INACH roofing education has an article on fasteners.
Copper should be used in the valleys and the fasteners.
at time when roofers are applying the slate to steep roofing decks they use galvanized straps to hold 2/4"s to act as roof jacks. If the galvanized straps are left behind I am told that it will effect the slate within it proximity.
Is this true, I do not know for fact. It is what I was taught only.
slate sizes and quality.

Slate is non vitreous so that makes sense Robert.

Bob I keep on commenting from memory and should be more subtle in my assumptions until I have solid fact.
I am just trying to help.
I hope it does.
Thanks Bob.
I worked large projects and laboured with seasoned slate installers. The tinsmiths always soldered galvanized and copper works.
I apprenticed 2 winters.
They knew I did not mind heights.
I watched and listened to them. That is how I received my trades.
I was told not to do something I knew it was for a reason.
I remember getting blasts from foremen when I did something wrong at the beginning. Most quite the job from such yelling matches. I just apologised and moved on.
I learned quickly to do as asked and listen.

Explain please.

Porous and more likely to soak up or absorb.

Reading earlier text on the material when this post came out they (various threads) recommending sealing the natural slate product.
If it is manufactured slate that would be different as I am sure resins would have a repellent effect.

Did not see any info tech or otherwise on using the flaky easy to split stone product as siding however but roofing I am sure would be the same as well as flooring which is more popular.
Seems the stuff splits so well that thin sheets are easily made which is desirable in many cases.

Another little fact I recall is that it often has natural variations in thickness from the splitting process.

Thanks Bob.

rusting pyrites.
A little more.
Looks like I might have been ahead of myself.