Answer

To make Methyl orange powder into solution:
 Use 0.4 - 0.5g of Methyl orange per litre, dissolved in 50 : 50 distilled/deionised water : IDA (Industrial Denatured Alcohol - also known as IMS or Industrial Methylated Spirit).
 Dissolve the powder in warm distilled/deionised water first (approx. 50oC should be fine) then add the IDA (not warmed) and mix well.

 Our ready-made solution only has about 25% IDA, the rest being water, so you may be able to use less Meths than in the recipe above.