Save a List of colors

Hi all - any help greatly appreciated on why this doesn't work.
I have a game with 11 additive scenes - each scene has a List of GameObjects that they pass to a static controller on loading and when the user clicks save i need to iterate through that list and find out the gameobjects material color and save it to disk (android). Save function .....

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. using System.Collections.Generic;
4. using System.Runtime.Serialization.Formatters.Binary;
5. using System.IO;
6.  
7. [System.Serializable]
8. public static class SaveLoad {
9.     public static List<Color> coloursUsed = new List<Color>();
10.     public static Color thisColour;
11.  
12.     public static void Save(int page) {
13.         SaveLoad.coloursUsed.Clear();
14.         foreach(GameObject go in globals.colourables){
15.                     SaveLoad.thisColour = go.GetComponent<Renderer>().material.color;
16.                     SaveLoad.coloursUsed.Add(SaveLoad.thisColour);
17.         }
18.         BinaryFormatter bf = new BinaryFormatter();
19.         FileStream file = File.Create(Application.persistentDataPath + "/page_" + page + ".gd");
20.         bf.Serialize(file, SaveLoad.coloursUsed);
21.         file.Close();
22.     }

This is the final piece of the development before launch