In your darkroom you also have to control the humidity level. Up to about 50% relative humidity is acceptable, however around 30-45% is ideal. One of the components of emulsion is water. When you are at the drying stage, you are trying to evaporate the water out of the emulsion. When your humidity level is too high, you will not be able to pull the water out of the emulsion, on the screen. Which will cause the screen to degrade at the washout stage. If you live in a questionable humidity area, purchase a humidity gauge to insure you can achieve the correct level. If your level is high, you should purchase a de-humidifier to bring the level down to a reasonable range.