How many blotters and corrugates do I need for a field trip?

You need (number of specimens × duplicates) corrugated cardboard pieces, and 2 × (specimens × duplicates) blotter sheets — one blotter on each side of the newspaper packet. For succulent-heavy trips, budget an extra blotter per unit for changing during drying. Always bring a 10–20% surplus.

How much does it cost to mount herbarium specimens?

The University of Florida Herbarium (FLAS) estimates $6–8 per specimen for professional processing including mounting, labeling, and accession. For DIY mounting, the main costs are archival mounting paper (~$0.54–$0.69/sheet from University Products) and PVA adhesive or gummed linen tape (~$0.05–$0.10/specimen). Archival label paper and ink add a few cents per label.

What is a press 'unit' in herbarium practice?

A press 'unit' is the repeating layer sandwich for one specimen: one corrugated cardboard ventilator sandwiched between two blotter sheets, with a single folded newspaper holding the specimen laid on the lower blotter. Units are stacked until the press is full, then the whole stack is clamped with straps or wing-nut bolts to apply even pressure.

Plant Press Capacity & Herbarium Supply Planner

Calculate specimen capacity, layer counts, supply quantities, and mounting budget for your herbarium collecting project.

Units:

Press Dimensions

Internal press depth (in)

Space between the two end boards when strapped shut. A standard wooden press is often 6–8 in deep.

End board thickness (×2) (in)

Each plywood end board is typically 0.5–0.75 in thick. Enter one board's thickness; both ends are counted.

Layer Thicknesses Per Unit

Corrugated cardboard (in)

Standard B-flute corrugated ventilator ≈ 0.18 in (4.5 mm).

Blotter paper (×2 per unit) (in)

One blotter ≈ 0.03 in (0.8 mm); two per unit = 0.06 in.

Folded newspaper (per specimen) (in)

One folded sheet ≈ 0.04 in (1 mm). Use one fold per specimen.

Fresh specimen bulk (in)

Average compressed thickness of your fresh plant material. Thin grass/flowers ≈ 0.15 in; average herb ≈ 0.35 in; succulent stem ≈ 0.75–1.5 in.

Field Trip Plan

Target species / collections

How many distinct plant collections you plan to press.

Duplicates per collection

Professional practice: press ≥3 duplicates per collection for distribution and identification. Home collectors: 1–2.

Number of presses available

Supply Costs (editable)

Cost per 100 corrugated cardboards

e.g. University Products B-Flute Corrugated Ventilators ≈ $49.30/100.

Cost per 100 blotter sheets

e.g. University Products cotton blotting paper ≈ $51.45/100.

Cost per 100 mounting sheets

e.g. 100% rag herbarium mounting paper ≈ $54–$69/100. Enter your vendor's price.

Cost per bottle of PVA adhesive

e.g. Lineco Neutral pH Adhesive 8 oz ≈ $18. One bottle mounts ~150–200 specimens.

Specimens mounted per glue bottle

Supply surplus buffer (%)

Add a percentage buffer above calculated minimums for damaged, spoiled, or extra material.

Specimens per press

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Total specimens pressed

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Presses needed

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Est. supply cost

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materials only

Supply Item	Qty (min)	+Buffer	Est. Cost

Method: Each press unit = 1 corrugated cardboard ventilator + 2 blotter sheets + 1 folded newspaper + fresh plant material. Capacity = floor((internal depth − 2×end board) ÷ unit thickness). Total specimen slots = capacity × presses. Supply quantities are derived from total pressed specimens (species × duplicates) plus your surplus buffer. Costs scale from your per-100-unit prices. Source: University of Florida Herbarium (FLAS) and Anderson (ABLE, 2003).

How to Use This Planner

Set your press dimensions. Measure the internal depth of your press — the space between the two end boards when strapped shut. Enter each end board's individual thickness (the tool doubles it automatically).
Adjust layer thicknesses. The defaults match standard B-flute corrugated cardboard (≈ 0.18 in / 4.5 mm) and cotton blotting paper (≈ 0.03 in / 0.8 mm each). Change the specimen bulk if you're pressing unusually thick or thin material.
Enter your collecting plan. Set how many species you intend to collect, how many duplicates per collection (professional practice: ≥3), and how many presses you have available.
Edit supply costs. The defaults are real prices from major herbarium suppliers (University Products, Lineco). Update them to match your vendor's current quote.
Read the results. The top cards show capacity per press, total specimens, presses needed, and estimated supply cost. The table gives a line-by-line shopping list with buffer quantities.

Why This Matters: The Plant Press Layer Stack

A plant press works as a repeating sandwich. Each "unit" consists of a corrugated cardboard ventilator, two blotter sheets, and one folded newspaper containing the specimen. The corrugations run side-to-side to let moist air escape, the blotters draw moisture out, and the newspaper keeps the specimen contained and labeled. Units stack until the press is full, then straps are cinched to apply even pressure across all layers.

Getting the layer count wrong causes two common problems: under-loading (wasted capacity on a field trip) and over-loading (specimens not pressed flat because the strap can't close enough). This calculator prevents both by working from your press's actual measured depth.

Standard Press & Sheet Sizes

The standard North American plant press frame is 12 × 18 inches (30.5 × 45.7 cm). This accommodates specimens pressed to fit a standard herbarium mounting sheet of 11.5 × 16.5 inches (29.2 × 41.9 cm). International herbaria often use a slightly different standard of approximately 29 × 43 cm for mounting sheets. Both sheet standards share roughly the same usable area.

If a plant specimen is too large, it is folded into a "V" or "W" shape, or cut into multiple numbered segments each mounted on a separate sheet (e.g., "Sheet 1 of 3").

Duplicates: Why Collect 3 or More?

Professional botanists typically press a minimum of three duplicate specimens per collection, especially in poorly-known regions. One set is deposited at the host-country or primary herbarium, one goes to the researcher's home institution, and additional duplicates are sent to specialists for identification or exchanged with partner herbaria. For citizen scientists building a personal or school collection, one or two duplicates per collection may be sufficient.

Blotter vs. Newspaper: When to Use Each

Newspaper alone is sufficient for most thin-stemmed herbaceous plants when you have a heated dryer. Add dedicated blotter paper for succulent or moisture-heavy material (lilies, cacti, fleshy fruits), or when working in humid conditions without forced-air drying. For extremely succulent material, plan to change blotters daily during the first few days of drying.

FAQ

How many specimens fit in a standard plant press?

It depends on the press's internal depth and the bulk of your plant material. For a typical 6-inch-deep wooden press with herbaceous specimens (≈ 0.35 in fresh bulk), this calculator estimates roughly 10–13 specimens per press. Thinner material like grasses can yield 15–20; succulent stems may reduce capacity to 5–8.

What is the standard herbarium sheet size?

The North American standard herbarium mounting sheet is 11.5 × 16.5 inches (29.2 × 41.9 cm). The international standard used by many European and tropical herbaria is approximately 29 × 43 cm. Plant presses are built slightly larger — 12 × 18 inches — to allow a small margin around the specimen inside the press.

How thick is one plant press layer (one specimen unit)?

A single press unit consists of one corrugated cardboard ventilator (~4–5 mm / 0.18 in), two blotter sheets (~1.6 mm total / 0.06 in), one folded newspaper (~1 mm / 0.04 in), and the fresh plant itself (3–15+ mm depending on species). For a typical herbaceous plant, the entire unit averages about 12–15 mm (0.5–0.6 in).

How many corrugates and blotters do I need per specimen?

You need one corrugated cardboard ventilator and two blotter sheets per specimen (one blotter on each side of the newspaper). For a field trip of 20 species with 3 duplicates each (60 total pressed specimens), you'd need 60 corrugates and 120 blotters at minimum, plus a 15–20% surplus buffer for damaged or soiled material.

How much does herbarium mounting cost per specimen?

Professional processing at a university herbarium (including mounting, labeling, and accession) costs roughly $6–$8 per specimen, according to the University of Florida Herbarium. DIY mounting costs mainly the mounting sheet (~$0.55–$0.70 each) and a few cents of PVA adhesive per specimen. Labels on archival cotton paper add a few more cents if printed in-house.

What is the drying time for pressed plant specimens?

Thin herbaceous plants typically dry in 24–48 hours with a forced-air plant dryer operating at 95–113°F (35–45°C). Without heat, air-drying takes 1–4 weeks. Succulent material may take longer and benefits from daily blotter changes in the first days. A specimen is ready when it is no longer limp and feels papery and rigid.

Can I use newspaper instead of blotter paper?

Yes, for non-succulent material with a heated dryer, a single fold of newspaper both contains and dries the specimen adequately — this is standard practice for many collecting expeditions. Dedicated blotter paper absorbs moisture more efficiently and is recommended for succulent plants, humid climates, or when a dryer is unavailable. Never use glossy or coated paper.

This tool provides estimates for planning and budgeting purposes only. Supply prices change frequently — verify with your vendor before purchasing. Drying times and layer capacities vary with plant material, climate, and equipment. Consult your receiving herbarium's guidelines before preparing voucher specimens.