The datasheet for finished venetian blinds lists six or eight numbers, and most buyers compare the first one. That is the mistake this page is about: the numbers interact, and the one you ignore is usually the one that produces the claim.
Finished blinds: why the headline number is the least useful one
Every quotation leads with headrail. But it tells you almost nothing on its own: headrail sets the frame, and the parameters below set whether the product survives its first year in service.
For finished blinds, the practical rule is to fix the headline figure at the level your product needs and then spend your negotiating attention on ladder tape / cord and cord lock.
The finished blinds numbers that decide performance
| Parameter | Typical range | What it changes | Headrail | 25 mm steel or aluminium | Steel is stronger and rusts; aluminium is lighter and costs more. | Slat | 25 / 35 / 50 mm, wood or PVC | The material decision cascades into weight, price and warranty. | Ladder tape / cord | polyester, 12-25 mm | Tape width affects the visual and the cord friction. | Cord lock | standard / auto-lock / cordless | The component that fails first in cheap blinds. | Bottom rail | wood, PVC, or aluminium | Weight affects how the blind hangs and how it operates. | Child safety | cordless / tension device / short cord | Mandatory in the EU, US, Canada and Australia, with different rules in each. | Width tolerance | 1-2 mm on the finished blind | Recess fitting needs the tighter end of this. | Valance | coordinated or hidden | A cosmetic choice that also protects the headrail in transit. |
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Headrail
Typical range: 25 mm steel or aluminium. Steel is stronger and rusts; aluminium is lighter and costs more.
Slat
Typical range: 25 / 35 / 50 mm, wood or PVC. The material decision cascades into weight, price and warranty.
Ladder tape / cord
Typical range: polyester, 12-25 mm. Tape width affects the visual and the cord friction.
Cord lock
Typical range: standard / auto-lock / cordless. The component that fails first in cheap blinds.
Bottom rail
Typical range: wood, PVC, or aluminium. Weight affects how the blind hangs and how it operates.
Headrail: range, tolerance and the clause
For Finished venetian blinds, the working range is 25 mm steel or aluminium.
What 25 mm steel or aluminium does not tell you
| Position | Value | Effect on finished blinds | Where it shows up | Floor | 25 mm steel or aluminium | Lowest cost, least margin for process variation; measured on slat width, 25, 35 or 50 mm | Cord lock slipping within a season | Working middle | 25 mm steel or aluminium | Predictable performance at a normal price; held at slat width, 25, 35 or 50 mm | Nothing to negotiate, nothing to explain; read against slat width, 25, 35 or 50 mm | Ceiling | 25 mm steel or aluminium | Best performance, highest cost; written as slat width 25, 35 or 50 mm | Cost the end product may not recover; measured on slat width, 25, 35 or 50 mm |
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The figure that decides the outcome is not headrail itself but the tolerance around it. A supplier who quotes 25 mm steel or aluminium without a tolerance has not quoted a specification, and the first lot will define the tolerance for you.
How to measure headrail
The reference method here is Operation cycles, run to internal 5000 cycles, with an acceptance of no slip, no fray.
A marginal pass on headrail tells you the process is running at the edge, which is the information you need before the next lot rather than after it.
The clause to write for headrail
Headrail 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
Slat: range, tolerance and the clause
For Finished venetian blinds, the working range is 25 / 35 / 50 mm, wood or PVC.
How to choose a slat option
| Option | What it changes in finished blinds | When it is the right choice |
|---|---|---|
| 25 mm | 25 mm is the entry point in finished blinds: a plastic cord lock and a steel headrail without coating. That is where the cord lock slipping under load starts. | Cost-led finished blinds programmes with a short service life. |
| 35 mm | 35 mm is the volume middle for finished blinds: enough margin for process variation without paying for headroom the end product cannot use. | Most repeat finished blinds programmes, and the safest default. |
| 50 mm | 50 mm is the top of the finished blinds family, where the process is controlled tightly enough to guarantee it. | A warranty, a tender, or a finished blinds specification that cannot be renegotiated. |
Slat 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.
The figure that decides the outcome is not slat itself but the tolerance around it. A supplier who quotes 25 / 35 / 50 mm, wood or PVC without a tolerance has not quoted a specification, and the first lot will define the tolerance for you.
How to measure slat
The reference method here is Child safety, run to EN 13120 / 16 CFR 1120, with an acceptance of pass for destination market.
A single sample from the top of a roll tells you about the top of that roll, and slat varies more across a run than most buyers expect.
A marginal pass on slat tells you the process is running at the edge, which is the information you need before the next lot rather than after it.
The clause to write for slat
Slat appears with a tolerance and a test, not as a standalone number.
Cord lock: range, tolerance and the clause
For Finished venetian blinds, the working range is standard / auto-lock / cordless.
How to choose a cord lock option
| Option | What it changes in finished blinds | When it is the right choice | standard | Safety device failure is where it usually ends up. | Cost-led programmes with a short service life; read against slat width, 25, 35 or 50 mm | auto-lock | The volume middle: enough margin for process variation without paying for headroom the end product cannot use; written as slat width 25, 35 or 50 mm | Most repeat programmes, and the safest default; measured on slat width, 25, 35 or 50 mm | cordless | The top of the family, where the process is controlled tightly enough to guarantee it; held at slat width, 25, 35 or 50 mm | A warranty, a tender, or a specification that cannot be renegotiated; read against slat width, 25, 35 or 50 mm |
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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.
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.
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.
The clause to write for cord lock
Cord lock appears with a tolerance and a test, not as a standalone number.
Ladder tape / cord: range, tolerance and the clause
It also explains why ladder tape / cord is the first line a buyer loosens and the last line a claim refers to.
For Finished venetian blinds, the working range is polyester, 12-25 mm.
What polyester, 12-25 mm does not tell you
| Position | Value | Effect on finished blinds | Where it shows up | Floor | polyester, 12 | Lowest cost, least margin for process variation; written as slat width 25, 35 or 50 mm | Blind not square within a season | Working middle | polyester, 12-25 mm | Predictable performance at a normal price; measured on slat width, 25, 35 or 50 mm | Nothing to negotiate, nothing to explain; held at slat width, 25, 35 or 50 mm | Ceiling | 25 mm | Best performance, highest cost; read against slat width, 25, 35 or 50 mm | Cost the end product may not recover; written as slat width 25, 35 or 50 mm |
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The figure that decides the outcome is not ladder tape / cord itself but the tolerance around it. A supplier who quotes polyester, 12-25 mm without a tolerance has not quoted a specification, and the first lot will define the tolerance for you.
How to measure ladder tape / cord
The reference method here is Squareness, run to diagonal measurement, with an acceptance of <= 2 mm difference.
A single sample from the top of a roll tells you about the top of that roll, and ladder tape / cord varies more across a run than most buyers expect.
A marginal pass on ladder tape / cord tells you the process is running at the edge, which is the information you need before the next lot rather than after it.
The clause to write for ladder tape / cord
Ladder tape / cord appears with a tolerance and a test, not as a standalone number.
Bottom rail: range, tolerance and the clause
For Finished venetian blinds, the working range is wood, PVC, or aluminium.
What wood, PVC, or aluminium does not tell you
| Position | Value | Effect on finished blinds | Where it shows up | Floor | wood, PVC, or aluminium | Lowest cost, least margin for process variation; measured on slat width, 25, 35 or 50 mm | Cord lock slipping within a season | Working middle | wood, PVC, or aluminium | Predictable performance at a normal price; held at slat width, 25, 35 or 50 mm | Nothing to negotiate, nothing to explain; read against slat width, 25, 35 or 50 mm | Ceiling | wood, PVC, or aluminium | Best performance, highest cost; written as slat width 25, 35 or 50 mm | Cost the end product may not recover; measured on slat width, 25, 35 or 50 mm |
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The figure that decides the outcome is not bottom rail itself but the tolerance around it. A supplier who quotes wood, PVC, or aluminium without a tolerance has not quoted a specification, and the first lot will define the tolerance for you.
How to measure bottom rail
The reference method here is Colour match, run to D65 + dE, with an acceptance of dE <= 1.5.
A single sample from the top of a roll tells you about the top of that roll, and bottom rail varies more across a run than most buyers expect.
A marginal pass on bottom rail tells you the process is running at the edge, which is the information you need before the next lot rather than after it.
The clause to write for bottom rail
Bottom rail appears with a tolerance and a test, not as a standalone number.
How to write a finished blinds specification that protects you
For finished blinds, the clause has to pin ladder tape / cord and cord lock, because those two separate a compliant lot from an adequate one:
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
Finished blinds: where the specification usually breaks down
The first failure is cord lock slipping. The blind creeps down and will not hold position. The cause is usually cheap zinc die-cast lock or a cord that is out of specification for diameter. The test that exposes it before you order: Cycle test 5000 up/down operations with a 5 kg load.
The second is ladder cord fraying. The cord fuzzes and breaks at the headrail. It comes from sharp edges on the headrail or an undersized pulley. Test with Visual inspection after 3000 cycles; measure cord abrasion.
What to put in a finished blinds enquiry
- End use and the conditions, which together decide where ladder tape / cord has to sit inside polyester, 12-25 mm.
- The one figure that must hold, with operation cycles named as the proof.
- Quantity per colour and per delivery, against a typical MOQ of 200-500 sets per size and colour.
- Destination market, because compliance changes the construction, not just the paperwork On finished blinds that is slat width at 25, 35 or 50 mm.
- A physical standard viewed under a stated light source, not a screen proof For finished wooden blinds it is headrail at 25 mm steel or aluminium that settles it.
Full ranges sit on the finished blinds page, and the manufacturing side of the same question is on our quality control page.
Questions buyers ask before ordering
Does tolerance move between the finished specification explained sample and bulk?
On finished specification explained, our engineering position on tolerance is 25 mm; the batch record is what proves it after the sample is gone.
What happens to finished specification explained if we need tolerance tighter than 25 mm?
On finished specification explained, the number to put on the PO is tolerance 25 mm, with the method named alongside it.
Is 25 mm a limit or a typical value for finished specification explained?
On finished specification explained, we hold tolerance at 25 mm across repeat lots.
Finished blinds: failure modes worth a clause in the purchase order
| Failure | What triggers it | Test to demand on the production lot | Cord lock slipping | Cheap zinc die-cast lock or a cord that is out of specification for diameter; held at slat width, 25, 35 or 50 mm | Operation cycles — internal 5000 cycles; acceptance no slip, no fray | Ladder cord fraying | Sharp edges on the headrail or an undersized pulley. | Child safety — EN 13120 / 16 CFR 1120; acceptance pass for destination market |
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The other two, with acceptance numbers attached, are in the full failure analysis for finished blinds.
Need finished blinds quoted against your specification?
Send the slat width and the destination market. The reply states the range we hold, the price at that volume, and which test report travels with the goods.
Products in this range
Related reading
- What Basswood Really Costs: A Line-by-Line Breakdown
- MOQ and Lead Time in Textile and Window Covering: How the Numbers Are Actually Built
- Cotton and T/C Fabric Guide: Yarn Count, Density and Shrinkage
Catalogue and current price list · Neutral packing and private label · Consolidation, documents and lead times
