Ethol LPD

Ethol LPD (Long Print Developer) is the modern long-life paper developer — designed for the same multi-hour tray-life property as the historical Ansco 130, but with a neutral-to-slightly-warm tonal character closer to Dektol than to Ansco 130's warm-brown. LPD has been the choice of high-volume and workshop printers since its mid-1970s introduction by Ethol Chemicals (now part of the Sprint Systems chemistry line), offering Ansco 130's tray longevity without committing to the dramatic warm-tone shift.^[1]

LPD's signature operational property is the 8+ hour active tray life — comparable to Ansco 130 and substantially longer than Dektol's 2-3 hours. This makes LPD the practical default for all-day printing sessions (workshop instruction, portfolio production runs, gallery exhibition prep) where mixing fresh trays mid-session would interrupt the workflow. The capacity per liter is also higher than Dektol — typically 30-40 8x10 prints per liter at 1:2 working dilution before noticeable activity drop.

The trade-off vs Ansco 130: LPD's tonal character is neutral-slightly-warm rather than Ansco 130's distinctive warm-brown. Photographers who want the long tray life and the warm-tone aesthetic still choose Ansco 130; photographers who want the long tray life with neutral printing choose LPD. The two developers serve different aesthetic goals.

LPD is supplied as a liquid concentrate by Ethol/Sprint Systems and dilutes 1:2 from concentrate to working solution. The liquid form is more convenient than Ansco 130's powder mixing for printers who don't want to maintain individual chemistry inventories.

When to choose Ethol LPD over Ansco 130 or Dektol

LPD sits between Ansco 130 (warm-tone, long tray life) and Dektol (neutral-cool tone, short tray life):

• vs Ansco 130: Both have 8+ hour tray life. LPD is neutral-slightly-warm; Ansco 130 is dramatically warm-brown. Choose LPD when you want neutral prints with long tray life; Ansco 130 when you want the warm-brown aesthetic.
• vs Dektol: Both are neutral-toned. Dektol has short tray life; LPD has long tray life. Choose Dektol for shorter sessions where the warmth difference doesn't matter; LPD for longer sessions where mixing fresh trays would interrupt workflow.
• vs Selectol-Soft: Selectol-Soft is the soft glycin developer for shadow detail; LPD is the contrast developer. Choose Selectol-Soft for two-tray printing; LPD for single-tray printing.

The phenidone-based long-life chemistry

LPD's chemistry uses Phenidone (rather than Metol) as the primary developing agent, similar to other modern paper developers but with specific buffering for extended tray life:

• Phenidone at low concentration — the primary developing agent
• Hydroquinone at moderate concentration — the regenerating partner (PQ superadditivity, same mechanism as in Microphen film developer)
• Sodium sulfite at high concentration — preservative + mild alkali + provides solvent action
• Mild buffer system — keeps pH stable as developer carry-over from prints accumulates over a long session, the property that distinguishes LPD from short-life developers

The PQ chemistry produces neutral-to-slightly-warm tonal character — Phenidone's silver-grain interaction shifts tone slightly warm vs MQ developers' more neutral character. The slight warmth differentiates LPD from pure-neutral Dektol.

Working-solution and tray workflow

Standard reference times in LPD working solution at 20°C:

Paper type	Dilution	Time
Fiber neutral-tone	1:2 from concentrate	90-120 sec
Fiber warm-tone	1:2	120 sec (slightly warmer than on neutral paper)
RC paper	1:2	45-60 sec
Higher-contrast variant	1:1 from concentrate	60-90 sec for fiber

Capacity per liter (working solution at 1:2):

• ~30-40 8x10 fiber prints
• 8+ hour tray life under normal use
• Watch for slowing development time as the indicator of bath exhaustion (fresh LPD develops at the published times; exhausted LPD takes 30%+ longer)

Practical notes

• Liquid concentrate convenience: LPD's liquid form is its operational advantage over Ansco 130. Mix 1L working solution from 333 ml concentrate + 666 ml water in seconds, vs 5+ minutes of powder dissolution for Ansco 130.
• Concentrate keeps 1+ year sealed; opened concentrate keeps 6 months in tightly-sealed full bottles.
• Working solution discards at end of session — even with 8+ hour tray life, working solution doesn't keep overnight. Mix fresh per session.
• Tray temperature 20°C — moderately temperature-sensitive; ±1°C affects time by ~5%.
• Use citric or acetic stop bath — LPD is less sensitive to developer carry-over than Dektol but a stop bath still extends tray life.
• PPE: nitrile gloves and eye protection. Phenidone is a known sensitizer; cumulative exposure during high-volume printing is a documented concern.

Related recipes

• [[recipe-ansco-130|Ansco 130]] — warm-brown alternative with similar long tray life
• [[recipe-dektol-d-72|Dektol (D-72)]] — neutral-cool alternative with short tray life
• [[recipe-selectol-soft|Selectol-Soft]] — soft glycin alternative for two-tray shadow detail
• [[recipe-amidol-paper-dev|Amidol Paper Developer]] — warm-neutral single-tray alternative; very short tray life