After the ten questions, what is the last thing to confirm before paying?

The paper trail: a contract that names the batch number, the sealed sample, the shade range, the load date, and the breakage policy — each in a line. When the payment lands, ask for container loading photos and document copies. That is the ten-question spirit applied one last time, on the day the money moves.

Questions to Ask a Roofing Slate Supplier: 10 Questions That Do the Filtering for You

Q: What if the supplier answers all ten questions perfectly?

Then you have done your homework and you can negotiate. A perfect answer sheet is rare; the honest ones will always miss one or two, and then admit it in writing. That is a better sign than perfection — it means they are not scripting you. Move forward, and ask the same ten questions against the contract before you sign.

Q: Do I need to visit the factory to verify?

No — but it is the strongest version of the third question. For most importers, remote verification with video, batch-matched reports and a sealed sample is enough. The factory visit becomes worthwhile at a scale where one container of wrong slate costs more than the flight.

I've spent the last fifteen years on the buyer's side of the slate table — sitting in on factory visits in Wales, Spain, India and Jiangxi, listening to suppliers answer questions, and watching which answers turned out to be true. Here's what I've learned: a roofing slate supplier is a little like a witness in court. You don't have to prove anything about them. You just have to ask the right questions and let them talk. Bad suppliers talk their way out; good suppliers talk their way in.

This isn't a buying guide — that lives at Roofing Slate Buyer's Guide — and it's not a how-to-source manual either. This is a script. Ten questions you can copy, in the order they do the most damage to a bad answer, with the passing line for each one. If you've never asked a supplier a serious question in your life, start here.

The short version first. These are the ten, and what each one quietly filters out:

1. "Which part of the quarry are you cutting now?" — filters out brokers who've never seen the mountain.
2. "Where did your last container go — and can I call the client?" — filters out fake factories with no track record.
3. "Can you send a video of today's production line?" — filters out anyone working from a brochure.
4. "Which batch number is on this test report?" — filters out circulated PDFs and borrowed certificates.
5. "How many color shades are you allowed to ship?" — filters out inconsistent sorting.
6. "Will the sample I approve be the standard you produce to?" — filters out sample-baiting.
7. "What exactly does this FOB price cover?" — filters out quotes with invisible extras.
8. "When can you actually load the container?" — filters out resellers with no production slot.
9. "Why is your MOQ one container?" — filters out scripted, not-shipped answers.
10. "What happens if more than 3% break at my port?" — filters out suppliers who never hear about the damage.

Read them, re-read them, and then let's walk through each one with the follow-up that matters.

The one rule behind all ten

Before the questions, the philosophy: never ask a supplier anything you could find out by reading. Look at their website, their test results page, their container photos. Use the ten questions only where reading can't reach — the gaps between their brochure and the truth.

And the second part of the rule: a question is only a question if you can follow it up. The real skill isn't the question, it's the follow-up. "And then?" is the most powerful sentence in supplier vetting. Ask it twice and most answers start to wobble. A good supplier's third answer is still consistent with the first. That's your signal.

Group one — is this supplier the thing they say they are?

Q1. "Which part of the quarry are you cutting from right now?"

A genuine quarry-driven producer can answer this instantly: the layer, the face, the block size, sometimes the geologist's name. They live there. A trader says "we have multiple sources," which is true of everyone and reveals nothing.

Passing line: they name a specific working face and offer to show it on video or photos from this week. A trader can't point to a face that doesn't belong to them.

The follow-up: "Send me a photo of today's quarry face with the date on a piece of paper." It takes them three minutes and proves more than any certificate. Yes, it's awkward — that's the point.

Q2 — "Where did your last container go, and can I speak to that client?"

Reference checks are the most under-used tool in slate buying. Most buyers stop at the website's happy customer logos. Ask instead for one real shipment, one real destination, and one contact name.

Passing line: they name a country, a port, a buyer type (roofing contractor, distributor, DIY chain) and offer to connect you — even with a small caveat like "the owner is in a different time zone." A trader with no history tries to change the subject, or offers a reference that's actually another buyer in the same group.

If you're shipping into the UK or Europe, this question also tells you something about their document flow — whether they've actually done European imports before. For a refresher on what the paperwork looks like, the sourcing guide maps the whole document trail.

Q3 — "Can you film your production line right now?"

This one is brutal and fair. Ten seconds of video from a phone, showing the cutting line, the sorting bench, the pile of finished slates. A genuine factory produces this in the afternoon. A paper company can't, because they have no line to film. Ask for today's production, not last year's marketing footage.

Passing line: the video arrives within a day, shows a real workshop with people, and matches the scale they claim. Bonus if you spot quality checks happening in frame — sorting tables, thickness gauges, rejected stacks.

Group 2 — does the product match the words?

Q4 — "What batch number does this test report belong to?"

Test reports are the most-circulated documents in the slate trade, and most of them are pictures of someone else's test. The question that cracks it open: which batch? A report tied to a batch number, a date, and a factory name can be matched against your order. A report with none of those is a decoration.

This matters whether you're buying EN 12326 for Europe or ASTM C406 for North America — the standard is only useful if it belongs to your batch, not a cousin's.

Passing line: they explain which batch the report covers, offer to send a report with their factory name on it, and — best — offer that the batch number on your packing list will match the report. When they don't, ask them to re-test. The good ones say yes without blinking.

Q5 — "How many color shades are you allowed to ship?"

Every natural slate deposit varies. The honest supplier knows their own variance — they sorted it into grades before they packed it. "We allow a variation of 2–3 shades within a shipment, and we box by shade" is a professional answer. "All our slates look exactly the same" is marketing talking, and it means they've never sorted a real load.

This dovetails with the color selection and mixing on site guides — but the point here is the question, not the theory. Ask the shade number, ask for the graded boxes, and then ask whether the shade boxes are labelled. Labeled boxes are the mark of a sorting line that works.

Passing line: a concrete shade range (e.g. "2–3 shades within a batch"), boxes separated by shade, and they don't promise uniform color like a synthetic product.

Q6 — "The sample I approve — will you seal it and produce against it?"

Samples are the single most reliable predictor of what arrives in your container — if you control them. The phrase to use is sealed sample (封样): the approved sample is kept at the factory, both sides sign it, and production must match it. It's a one-line agreement that has saved more shipments than any inspection.

Ask it as a question to see how they react. A supplier who's done this before says "of course, we'll seal one for you and one for ourselves." A supplier who's never thought of it goes silent while they invent a policy.

Passing line: they agree to seal the sample, keep it on site during production, and — the detail that counts — the sample's size and thickness measurement is written on the sealed card. Pair this with a delivery inspection and you've closed the loop.

Group 3 — the price, the clock and the small print

Q7 — "What exactly does this FOB price cover?"

Slate is quoted FOB (free on board) or CIF (cost, insurance, freight), and the difference is never just the freight. Between them sit port charges, terminal handling, documentation fees and the occasional creative addition. I've seen quotes where "FOB" quietly excluded the stuffing, the palletization, the container loading, or all three.

One hard number I keep from my years of reviewing quotations: the gap between a clean FOB quote and the port-side reality of an average supplier's quote often runs 3–5% — and I've seen 8% when the supplier knows you can't read the lines. The cheap price is the one that leaves no surprise at the loading dock.

Passing line: a line item breakdown: slate price, pallets, strapping, container stuffing, docs, local haulage to the port — each a number, not a lump. The next article in this series, How to Compare Roofing Slate Quotations, goes deep on this.

Q8 — "If I pay you today, when do you load?"

Lead time is the honest thermometer of capacity. A factory with a live production line tells you in days. A trading company starts a story about "the factory schedule" — because they're asking someone else. Ask the direct question, then the follow-up: "Is that written in the contract as a date, or a number of days after deposit?"

Passing line: a number in days from deposit to loading, in writing, with a penalty or at least a backstop if they slip. Vague "about two months" answers are a trader's blanket.

Q9 — "Why is your MOQ one container?"

Some MOQs are technical: a quarry's block yields a minimum, a production run has an economical batch. Others are commercial: the supplier wants to move the most slate, or can't process smaller orders profitably. Asking the why tells you which one you're dealing with, and it tells you whether a half-container request will be answered by a factory or a frustrated email from a trader.

If their MOQ logic is about blocks and yields — you can work with that. If it's "we always do one container," it's a habit, and you can test it. The full MOQ reasoning gets a guide of its own later in this series; for now, ask the why and listen to the silence.

Group 4 — money, damage and the paper that holds it

Q10 — "How do we pay, and what's your policy if 3% breaks at my port?"

Payment terms are the last filter, and the most concrete. The standard in the China slate trade is roughly 30% deposit and 70% before (or at) loading — and the variance between suppliers is a personality test. Ask them to say it out loud: "what do you need from me, in what order, and what do I get at each stage?"

Passing line: a clear payment structure with each payment tied to a deliverable — deposit with the signed contract, balance against the packing list and loading photos, and a warranty clause written into the PI (proforma invoice). The moment a supplier says "you'll be fine, we've never had a problem" without writing it down — that's when you need it in writing most.

On breakage: a well-packed 20-foot container of slate lands with roughly 1–3% transit damage as the normal band — slates are stone, and the ocean is a machine that shakes everything. The question is who owns the risk. "We stand behind our packing — over 3% and we replace" is a supplier who knows their packaging and their loading. "Damage is always the freight line's fault" is a supplier who never watches a container leave.

The follow-up that separates them

You now have ten questions and ten passing lines. But the whole method lives in one habit: when an answer is vague, don't accept it — repeat the question with the words "and then?"

"We have good quality." — And then? "…and we test every batch." — Can I see this batch's number? "…I'll send it tomorrow." — that tomorrow is your deciding moment.
"We can load in two weeks." — And then? "…after deposit." — Is that written into the contract? Silence. That's your answer.

Vague answers, deflected questions, and promises that live nowhere in writing are the same answer three times. Take it from someone who has read hundreds of quotations: the supplier who writes everything down, answers everything with a number, and lets the follow-up, is the supplier you can build a 100-year roof on.

Three last questions you can skip

Not every question deserves asking. These three are useless, and knowing it saves you credibility:

"Are you really a factory?" — They will all say yes. The license and the video are the proof; the question is just the hook for them to lie.
"What's your best price?" — On a first contact, it tells them you buy on price, which is exactly how the price gets up. Price after you've done the nine other questions.
"Do you have a quality certificate?" — everyone says yes. Ask instead for the batch number, the date, the name of the lab.

And one last habit from an old inspector: measure the sample yourself. When the sample box arrives, take out a rule and check length, width, thickness against the card. The supplier who is honest about 4.8 mm when you asked for 5 mm is a supplier you can talk business with. The supplier whose sample is 5.2 mm "to give you a better value" — is telling you exactly how the container will feel.

FAQ — the questions buyers ask me about asking

What if the supplier answers all ten questions perfectly?

Then you've done your homework and you can negotiate. The perfect answer sheet is rare; the honest ones will always miss one or two, and then admit it in writing. That's a better sign than perfection — it means they're not scripting you. Move forward, ask the same ten against the contract before you sign.

Should I ask all ten questions on the first call?

No. Spread them out. The first call should feel like a normal conversation; the ten questions are the spine of several exchanges. If you fire all ten in one email, you get a ten-line reply and no follow-up — which defeats the whole method. Start with Q1–Q3, then let the sample exchange pull the next group.

Are these questions for Chinese suppliers only?

Not at all. The script works for any supplier — Welsh, Spanish, Indian, Chinese. The quarry question and the "film the line today" question are universal; the FOB and deposit questions land hardest in China because that's where most of the world's roofing slate is loaded, but the logic travels.

Do I need to visit the factory to verify?

No — but it's the strongest version of Q3. For most importers, a remote verification with video, batch-matched reports and a sealed sample is enough. The factory visit becomes worthwhile at a scale where one container of wrong slate is more expensive than the flight. The factory quality control guide shows you what a real visit should check.

What if they ask me questions back?

Welcome it. A supplier asking about your roof pitch, your climate, your sizes, and your expected quantities is a supplier who's actually planning production, not just taking an order. Answer them honestly — it feeds them the information they need to quote you straight. Beware the supplier who asks zero questions.

After the ten questions, what's the last thing to confirm before paying?

The paper trail: a contract that names the batch number, the sealed sample, the shade range, the load date, and the breakage policy — each in a line. When the payment lands, ask for the container loading photos and the copies of the documents. That is the ten-question spirit applied one last time, on the day the money moves.