Gary provides this simple function for converting unprintable characters with ASCII codes between 0 and 31 into spaces. It builds a string containing the disallowed characters surrounded by square brackets. It then uses regular expressions to match any of those characters and replace them with spaces.

Private Function CleanseData(ByVal textToCleanse As String, _
    _
 Optional ByRef changeCount As Integer = 0) As String
    ' Create illegal character string
    Dim badChars As String = String.Empty
    For index As Integer = 0 To 31
        ' Use ChrW instead of Chr to avoid boxing
        badChars &= ChrW(index)
    Next

    ' Build RegEx pattern - square brackets say match any
    ' one of them
    Dim pattern As String = "[" & badChars & "]"

    ' Are there any illegal characters
    If Regex.IsMatch(textToCleanse, pattern) Then
        ' Count them
        changeCount = Regex.Matches(textToCleanse, _
            pattern).Count
        ' Convert them to spaces
        textToCleanse = Regex.Replace(textToCleanse, _
            pattern, " ")
    End If
    Return textToCleanse
End Function 'CleanseData