Washable flame-resistant fabrics should only be washed in detergent, never soap. This is because soap's natural ingredients can react with the minerals in water to leave an insoluble film on the fabric, which can damage the flame-resistant finish.
Don't wash above 50°C and avoid soaking as this can also damage the flame-resistant finish. A liquid fabric conditioner can be used, but be sure to follow the care label instructions carefully.
Fabric softeners are not for use on children's sleepwear, or other garments labelled as flame resistant, as they may reduce flame resistance.
Trimmings on garments can affect how they are washed or which product is used. For example, if a garment has a leather collar the care label may say 'Dry Clean Only' even if the rest of the garment is washable.