Paulownia blinds and slats Specification: What Each Number Actually Changes

Buyers lose money on paulownia blinds and slats in a predictable way: they specify one figure tightly and leave the rest to the supplier. This is a walk through every figure that changes the outcome, in the order it matters.

Why the headline number is the least useful one

Every quotation leads with density. It is easy to compare and it is the number the factory can hit most cheaply. But it tells you almost nothing on its own: density sets the frame, and the parameters below set whether the product survives its first year in service. A buyer who compares only the headline figure is buying a sample, not a supply agreement.

For paulownia, the practical rule is to fix the headline figure at the level your product needs and then spend your negotiating attention on slat thickness and moisture content. Those two are where cheap goods differ from adequate goods, and they are usually absent from the quotation sheet.

The numbers that decide performance

Read the table as a set of trade-offs rather than a checklist. Moving any single line usually costs money somewhere else, and the cheapest way to hit one figure is often to let another slip.

Density

Typical range: 0.25-0.32 g/cm3. 40 % lighter than basswood, which cuts freight per set substantially.

Slat width

Typical range: 25 / 35 / 50 mm. 63 mm is possible but the material is soft for that span.

Slat thickness

Typical range: 2.5-3.2 mm. Needs more thickness than basswood to reach the same stiffness.

Moisture content

Typical range: 8-12 %. Paulownia moves faster than basswood, so equalising matters more, not less.

Grain

Typical range: straight, coarse pores. Coarse pores drink lacquer, so sealing coats are heavier.

How to write a paulownia specification that protects you

A specification is only useful if a substitution becomes visible. That means writing the construction and the performance together, and naming the test that proves each one. For paulownia, the clause has to pin slat thickness and moisture content, because those two separate a compliant lot from an adequate one:

Paulownia venetian blind, 50 mm slat, 2.8 mm, density 0.25-0.32 g/cm3, moisture 9-11 %, sanding sealer + 3 coats, warp <= 2.0 mm/m, cordless to EN 13120

Note what is missing from that line: adjectives. No ‘high quality’, no ‘premium’, no ‘export grade’. Every clause is either a number with a tolerance or a named test. If a supplier cannot quote against a line written this way, that is information about the supplier.

Where the specification usually breaks down

The first failure is denting. Slats show dents and marks after a season of cleaning and use. The cause is usually low density and a soft early-wood layer. The test that exposes it before you order: Janka hardness and a drop test with a 50 g ball from 30 cm.

The second is warping. Slats cup or bow, faster than basswood in the same room. It comes from high moisture variation and a porous structure that absorbs quickly. Test with 48 h at 23 C / 50 % RH, then measure. and write the result into the purchase order, not just the enquiry.

Both failures share a pattern: they appear months after delivery, they are hard to attribute, and the cost lands on the buyer rather than the mill. That is exactly why the test belongs in the specification and the report belongs in the shipment file.

What to put in a paulownia enquiry

1. End use and the conditions, which together decide where slat thickness has to sit inside 2.5-3.2 mm.
2. The one figure that must hold, with moisture content named as the proof.
3. Quantity per colour and per delivery, against a typical MOQ of 300-500 sets per colour.
4. Destination market, because compliance changes the construction, not just the paperwork.
5. A physical standard viewed under a stated light source, not a screen proof.

With those five points we can quote against a real requirement instead of a generic range. Full ranges sit on the paulownia page, and the manufacturing side of the same question is on our quality control page.

Questions buyers ask before ordering

Why is paulownia cheaper than basswood?

Faster growth, higher availability and lower density, which also lowers freight. It is not a cheaper process; it is a cheaper raw material with different mechanical limits.

Can paulownia be used in hotels?

Only in low-traffic areas. It dents under cleaning and trolley impact. For guest rooms we quote basswood or PVC.

Does paulownia need a different finish?

Yes, a sanding sealer before the topcoats. Without it the coarse pores absorb unevenly and the finish looks dry.

Failure modes worth a clause in the purchase order

Claims rarely come from a batch that was obviously wrong. They come from a hardness figure that sat inside the quoted band and outside what the product needed.

The other two, with acceptance numbers attached, are in the full failure analysis for paulownia. A supplier who cannot name the mode he sees most often is describing a catalogue, not a process.

Seven lines that turn a quotation into a specification

Most post-delivery arguments are not about quality. They are about a document that never said which figure would be measured, on which instrument, at whose cost.

1. Warp tolerance (<= 2.0 mm per 1 m): state where in the band this order sits. The middle of the band is not what a tolerance is for.
2. Density: the figure you will accept inside the 0.25-0.32 g/cm3 band, the tolerance on it, and the method used to measure it.
3. Slat width (25 / 35 / 50 mm): name the number, not the word. If the answer only repeats the band, ask which point inside it is being offered for this order.
4. Slat thickness: 2.5-3.2 mm is the market band. Fix the figure you will test at goods-in, and the instrument you will test it with.
5. Price validity: the period during which the quoted figure holds, and what happens to it when the raw-material index moves.
6. Remedy: rework, replacement or credit, and the point at which each applies.
7. Sample retention: one production sample per lot stays with the mill for twelve months. Claims are settled against it, not against memory.

Related reading

• Moisture content in Paulownia blinds and slats
• Paulownia vs Basswood
• Slat width in Paulownia blinds and slats