It is a good practice to work on the underlying data source instead of modifying the data grid directly.
You have already created a data table so why not use it as the data source?
It should be something like this
C#
DataTable dtBarcodes = blOrderDetails.getProductsonBarcode(Convert.ToString(tbbarcode.Text));
dgvTextiles.DataContext = dtBarcodes.DefaultView;
XAML
<DataGrid Name="dgvTextiles" ItemsSource="{Binding}">