Development time

Ilford FP4 Plus in Ilfosol 3

8:30 at 20°C, 1+9 dilution, EI 200 (+⅔ stop).

Start timer · 8:30

Time

8:30

Standard

Dilution

1+9

Temperature

20°C

Box speed

ISO 125

B&W

Development time

Dilution	EI	Time	Temp	Agitation	Timer
1+9	200+⅔ stop	8:30	20°C / 68°F	Standard	Start timer

EI is the speed the film was rated at when shooting. Times marked “not yet verified” come from secondary sources and haven’t been checked against a manufacturer datasheet.

Other temperatures

18°C	19°C	20°C	21°C	22°C	23°C	24°C
10:38	9:31	8:30	7:39	6:48	6:07	5:32

Calculated from the 20°C time using Ilford’s temperature compensation factors, not taken from a datasheet. Most B&W developers behave well between 18°C and 24°C.

Mixing

Dilution	300 ml (one 35mm roll)	500 ml (one 120 roll)
1+9	30 ml developer + 270 ml water	50 ml developer + 450 ml water

How they work together

Ilfosol 3: High acutance, full film speed, medium-high contrast. Good general purpose results.
Ilford FP4 Plus: Often considered a benchmark for medium speed B&W. Notable sharpness and fine grain. Well-suited for high-quality enlargements.
Notes on this pairing: Pushed +2/3 stop.

FP4 Plus in other developers

ID-11