cannot convert from 'string' to 'Project.Models.Classname'

_coatlist = new ObservableCollection<Coat>(_mpackageManagerRepository.GetCoats(App.package, Specification, Product));

                foreach (Coat value in _coatlist)
                {
                    AllProducts.Add(value.ProductName);
                    AllProducts.Add(value.ThinnerNo);
                }

Model class:
public class Coat : TableData
{
public string ProductTypeName { get; set; }
public string ThinnerNo { get; set; }
}
This is my code. I am trying to add productname and thinner number in to a list. and I am getting error "cannot convert from 'string' to 'Project.Models.Classname'".

Please help me with this.