[header] How to clean an enamel bathtub [title] Mix hot water and liquid dishwashing soap. [step] Get out a small bucket and pour 2 tablespoons (30 ml) of gentle dishwashing soap into it. Use a dishwashing soap that will cut through grease and grime. 
Pour 1 gallon (3.8 liters) of hot water into the bucket. Stir the mixture until it's soapy and combined.