1. Single-environment likelihood
Start here to score one storage setup. Temperature and RH drive the base reaction rate; the modifiers let you nudge that up or down for the microenvironment. Condition / VS history is handled separately on the consequence side of your matrix.
Use the long-term average temperature for the cel (baseline reference is 70 °F).
Use the long-term average RH near the cel (baseline reference is 50% RH).
Captures how easy it is for vapor to clear the immediate microenvironment.
Only large, well-placed scavengers get a small credit; most real-world cases are neutral (1.0).
More coverage and stuck layers mean slower diffusion and more local acid recycling.
Match this to the consequence table in the risk framework: C answers “how bad is failure for this cel as it sits today?”
Base AH/T likelihood band (Lbase) from T/RH only: 3 (Neutral).
With 70 °F and 50% RH, this setup is roughly comparable to a conventional “good room” baseline. You are not in immediate danger territory, but you are also not buying much extra life.
k_rel ≈ 1.00 → L_base = 3. Microenvironment factor M_total ≈ 1.00 → L_eff = 3.
Think of Lbase as the pure AH/T likelihood for a stable cel. The microenvironment correction factors (geometry, scavenger, paint coverage) gently nudge this up or down to an effective Leff, clamped to [1,5]. Condition / VS history is handled on the consequence side below.
2. Compare two storage setups
Use this to sanity-check two different environments side by side. The calculator re-runs the same Arrhenius + absolute humidity logic (without correction factors) for each case and shows which one pushes the cel closer to the wear-out region of the bathtub curve. These scores are in terms of Lbase.
Setup A
Example: current room or frame.
Setup B
Example: target microclimate or cold storage.
With the defaults, Setup B is gentler on the cel than Setup A. Lower temperature and lower absolute humidity both slow the hydrolysis clock.
3. L × C Risk Matrix & Tier Guidance
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Interpreting L × C – Present Risk vs. Future Risk
The L × C score represents current risk, not long-term preservation outlook.
L (Likelihood) describes how aggressive the environment is – how quickly hydrolysis
will progress under the present temperature and humidity. C (Consequence) describes
the cel’s current physical condition and how vulnerable it is right now.
This means a cel can have a high L but low C and still show a low L × C score today.
However, a high L guarantees that C will rise over time if storage conditions are not
improved. Low current risk does not imply long-term safety.
Use the L × C matrix to understand today’s condition-based risk, and use the
lifetime model to understand how quickly the cel will move into higher-C states
under the same environment. When L is elevated, Tier 2 or Tier 1 storage is still
recommended to prevent future condition drift.
This section combines your effective likelihood band Leff with the consequence score C to give an overall risk band (L × C). The highlighted cell shows where this cel sits on the matrix. Use the text summary to map that band back to the preservation tiers.
| L \ C | C = 1 | C = 2 | C = 3 | C = 4 | C = 5 |
|---|---|---|---|---|---|
| L = 1 | 1 | 2 | 3 | 4 | 5 |
| L = 2 | 2 | 4 | 6 | 8 | 10 |
| L = 3 | 3 | 6 | 9 | 12 | 15 |
| L = 4 | 4 | 8 | 12 | 16 | 20 |
| L = 5 | 5 | 10 | 15 | 20 | 25 |
Current setting: Leff = 3, C = 1 → L × C = 3.
With a neutral environment (L = 3) and cosmetic-only damage (C = 1), overall risk is low. A Tier 3 storage approach is typically adequate; Tier 2 is optional insurance.
As a rough guide: very low scores (1–4) align with Tier 3+ baselines, mid scores (5–12) justify aiming for Tier 2 or better, and high scores (≥16) point toward Tier 1 strategies or active reset. See the main tier table for full definitions.
4. Methodology & scoring logic
How this tool thinks:
-
Convert your T/RH into a relative rate multiplier
k_relversus a 70 °F / 50% RH baseline, using Arrhenius plus an absolute humidity term. -
Map that rate into a 1–5 base band
L_base(neutral room ≈ 3, strongly protective → 1, aggressively damaging → 5). The likelihood table below applies to this base mapping only. -
Apply small, bounded microenvironment correction factors (storage geometry,
scavenger, paint coverage) to get an effective score
L_eff, clamped to [1,5]. Condition / VS history is intentionally kept separate for consequence/state.
Each dropdown contributes a dimensionless multiplier:
-
Storage geometry/volume:
M_storage ∈ {1.0, 1.1, 1.25, 1.4}— the “sealed” penalty applies only when there isn’t a strong scavenger inside; when a big scavenger is present, the tool cancels that penalty. -
Scavenger / MicroChamber / zeolite:
M_scav ∈ {1.0, 0.95, 0.9} -
Paint coverage / trapped layers:
M_geom ∈ {1.0, 1.1, 1.25, 1.4}
M_total = M_storage × M_scav × M_geom, and the effective likelihood band is:
L_eff = clamp( round(L_base × M_total), 1, 5 ).In practice,
M_total usually sits near 1.0, so you move at most one band up or down: a
tight, poorly ventilated stack with no scavenger can push a neutral AH/T band into “High,” while an
oversized scavenger in a well-designed enclosure can pull a marginal AH/T band back toward “Neutral.”
Base likelihood scale (Lbase) at a glance
| Lbase | Band | k_rel range (vs 70 °F / 50% RH) | Interpretation (AH/T only, before correction factors) |
|---|---|---|---|
| 1 | Very low | k_rel < 0.5 | AH/T environment is strongly protective. VS progression is much slower than the baseline 40–50 year horizon. |
| 2 | Low | 0.5 ≤ k_rel < 0.9 | Better than a neutral room. The hydrolysis clock is clearly slowed, but VS is still possible over very long spans. |
| 3 | Neutral | 0.9 ≤ k_rel ≤ 1.1 | Comparable to 70 °F / 50% RH storage. A “good room” but not truly life-extending. |
| 4 | High | 1.1 < k_rel < ~3.3 | Hydrolysis is running faster than baseline. VS onset within a collector-relevant horizon (30–50 years) is likely. |
| 5 | Very high | k_rel ≳ 3.3 | Roughly equivalent to a < 15 year horizon. The cel is being pushed quickly into the wear-out region; aggressive mitigation is justified. |