Serialize a string without (Instance)

Hello guys, I got a little problem, I'm trying to workaround Unity unability to serialize Materials, and I figured I could do it with strings and material names. Except when serializing a string, Unity always add (Instance) at the end of the name and thus it fuck up my name so when I try call it, I get the ugly pink material error.

In short:

• My material is named skin1

• I push save button

• Unity save the name as "skin1 (Instance)" in the file

• I try load it, it doesn't work because I ask for a name like "skin1" and it return "skin1 (Instance)"

My script is like so

     using UnityEngine;
     using System.Collections;
     using System.Collections.Generic;
     using System.Runtime.Serialization.Formatters.Binary;
     using System.IO;
     
     public class Manager : MonoBehaviour {
     
         public BinaryFormatter bf;
     
         // Use this for initialization
         void Start () {
         
         }
         
         // Update is called once per frame
         void Update () {
         
         }
     
         public void Saving(){
     
             SavedData dataa = new SavedData();
             dataa._skin = GameObject.Find("skin").GetComponent<Renderer>().material.name;
             //dataa._hair = GameObject.Find("hair").GetComponent<Renderer>().material;
             //dataa._wings = GameObject.Find("hair").GetComponent<Renderer>().material;
     
             BinaryFormatter bf = new BinaryFormatter();
             FileStream file = File.Create (Application.persistentDataPath + "/savedGames.json");
             bf.Serialize(file, dataa);
             file.Close();
     
     
         }
     
         public void Loading(){
     
             print("clack" + Application.persistentDataPath);
     
             if(File.Exists(Application.persistentDataPath + "/savedGames.json")) {
                 BinaryFormatter bf = new BinaryFormatter();
                 FileStream file = File.Open(Application.persistentDataPath + "/savedGames.json", FileMode.Open);
                 SavedData dataa = (SavedData)bf.Deserialize(file);
     
                 print("clack" + dataa._skin);
                 GameObject.Find("skin").GetComponent<MeshRenderer>().material = (Material)Resources.Load(dataa._skin, typeof(Material));
     
                 file.Close();
             }
                 
         }
     }

And this is my Serializable class

 using System;
 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine.UI;
 
 [Serializable]
 
 public class SavedData{
 
     public string _skin;
 
 }

it's incredibly annoying, since I got a lot of elements to save thus, and I got no idea how to remove that (Instance) in the name. Anyone can help?