Most finished blinds specifications treat cord lock as a single number. It is a distribution, and the width of that distribution is what your customer experiences after a year.
What cord lock actually controls in finished blinds
The component that fails first in cheap blinds.
The number is easy to quote and hard to hold, and the difference between those two things is what you are actually buying.
For Finished venetian blinds, the working range is standard / auto-lock / cordless. Inside that band the choice is commercial; outside it, the product changes category and so does the price.
How to choose a cord lock option
| Option | What it changes in finished blinds | When it is the right choice |
|---|---|---|
| standard | The lowest-cost option in the family. Safety device failure is where it usually ends up. | Cost-led programmes with a short service life |
| auto-lock | The volume middle: enough margin for process variation without paying for headroom the end product cannot use. | Most repeat programmes, and the safest default |
| cordless | The top of the family, where the process is controlled tightly enough to guarantee it. | A warranty, a tender, or a specification that cannot be renegotiated |
These are alternatives, not points on a scale. Cord lock is chosen by the application rather than by price, and a supplier who quotes one option as if it were interchangeable with another is quoting a different product.
Buyers default to the floor because it is the cheapest compliant answer. That is rational until the first claim, and then the saving is measured against a replacement shipment.
The figure that decides the outcome is not cord lock itself but the tolerance around it. A supplier who quotes standard / auto-lock / cordless without a tolerance has not quoted a specification, and the first lot will define the tolerance for you.
How to measure cord lock
The reference method here is Cord load, run to static load test, with an acceptance of per standard. The method is the easy part; sampling and conditioning are where reports diverge.
Condition the sample before measuring. Results in this family move by 10-20 % between a dry laboratory and a humid one, and two labs can disagree on the same material without either being wrong.
Record the measured value rather than pass or fail. A marginal pass on cord lock tells you the process is running at the edge, which is the information you need before the next lot rather than after it.
Cord lock does not stand alone
Cord lock moves with bottom rail (wood, PVC, or aluminium) and with child safety (cordless / tension device / short cord). Tightening one usually costs money in another, and a supplier who accepts every tolerance without comment has either not understood the interaction or is planning to substitute.
If a quotation is significantly cheaper, the difference is usually in one of these neighbours rather than in the figure being discussed.
The clause to write for cord lock
The line below is the version we can quote against without inventing anything. Cord lock appears with a tolerance and a test, not as a standalone number.
50 mm basswood venetian blind, 25 mm steel headrail, branded cord lock, 5000-cycle tested, cordless with tension device to EN 13120, square within 2 mm, stain 3A, valance included
A specification without a test method is a preference. It becomes a requirement when the method and the acceptance value are both named, because then a substitution is visible.
When cord lock goes wrong
Safety device failure. The tension device pulls out or the cord loop exceeds the limit.
The cause is usually device not tested to the destination market’s standard.
The test that catches it: EN 13120 mechanical tests; 16 CFR 1120 for the US.
What to specify instead: Test to the destination standard, not to a generic one, and keep the test report with the shipment.
The pattern is consistent: the failure appears months after delivery, is hard to attribute, and the cost lands on the buyer. That is the argument for measuring cord lock on every lot rather than on the development sample.
Four questions about cord lock, before you order
- What tolerance do you hold on cord lock, and what did your last three lots measure against it?
- Which method do you use for cord load, and which laboratory signs the report?
- When cord lock falls outside standard / auto-lock / cordless, do you rework, downgrade, or ship and hope?
- Which of bottom rail or child safety would you move first to hit a lower price?
The answers are more useful than a certificate, because they show whether the process is controlled or merely inspected. Full ranges for finished blinds are on the product page, and the measurement regime is described on the quality control page.
Questions buyers ask before ordering
How are blinds packed for sea freight?
Individual sleeve, carton with corner protectors, ISTA 1A drop tested. For humid routes we add a moisture barrier, because lacquer blushing in transit is a real claim category.
Which child-safety standard applies to my market?
EU/UK: EN 13120. US: 16 CFR 1120. Canada: CCPSA. Australia: the corded internal window coverings regulation. They are not interchangeable, and a generic certificate is not evidence.
From quotation to specification in seven lines
Leave the tolerance and the method out and every dispute is settled by whoever needs the goods more.
- Width tolerance: 1-2 mm on the finished blind is the market band. Fix the figure you will test at goods-in, and the instrument you will test it with.
- Valance (coordinated or hidden): fix the value per shipment, and state who pays for the re-test if a lot lands outside it.
- Headrail: 25 mm steel or aluminium is not an answer on its own. Ask for the last three lots’ actual readings and the spread behind them.
- Slat: agree the test method with the number. Two labs, two methods, two answers, one argument.
- Who inspects: third-party, in-house or none, decided in advance, with the AQL level written down.
- Reference sample: the signed sample is the definition of the colour, not the photograph in the catalogue.
- Price validity: the period during which the quoted figure holds, and what happens to it when the raw-material index moves.
Questions worth asking before the price is agreed
The questions below are the ones that cannot be answered from a catalogue, which is exactly why they are worth asking.
| Question | Answer that should worry you | Answer that holds up |
|---|---|---|
| Who signs the test report, and against which standard? | “Our QC department signs it.” | A named standard, a named method and a signature that belongs to somebody who can be asked again next year. |
| How do you hold valance at coordinated or hidden? | “That is standard for us, no problem.” | The last three lots’ readings, the instrument used and who signs the report. Safety device failure starts here. |
| What happens if slat misses the 25 / 35 / 50 mm, wood or PVC requirement? | “It will not happen.” | A re-test clause, the tolerance on the re-test, and the point at which the lot is remade rather than discounted. |
Need cord lock specified and tested against your end use?
Send a window schedule or a single set size and we will return a quotation with the loading plan, the safety standard that applies to your market and the lead time for the colour you need. Catalogue and current price list on request.
Related reading
- Finished venetian blinds
- Finished venetian blinds Specification
- Bottom rail in Finished venetian blinds
Catalogue and current price list · Neutral packing and private label · Consolidation, documents and lead times
