I have one form which has a text field in which I want to enter a file path (eg. C:UMydata ile name.jpg) it also has a field "Colours"

In another form, I want to select the "Colour" from a lookup field, and have the file path populate another field. 

When I do this, the backslash is dropped from the file path, so that it is populated like this: C:UserMydatafile name.jpg 

Is there any way to keep the text as entered? I would have thought because it was a text field, that this would happen? I have also tried entering the file path within " " and ' ' but neither method keeps the in the path?

Appreciate your help, 

Bianca