How actually work LayerMasks in Physics.Raycast ()?

Hello,

I want to find out if specific object was hit so I have GameObject and i want to read its layerMask. All is working to this point, but when I try to get this readed value into Physics.Raycast, its not working. I`ve tried it with public LayerMask so i had to choose it in Unity and it worked fine (but thats not what i want).

So is there any way to get Physics.Raycast work with LayerMask readed from GameObject?

 using UnityEngine;
 using System.Collections;
 
 public class SpeechBubbles : MonoBehaviour {
 
     private Camera cam;
     private LayerMask sourceMask1;
     private GameObject source1;
 
     public LayerMask testLayer;
 
     // Use this for initialization
     void Start () {
 
         cam = Camera.main;
 
         source1 = GameObject.Find ("Trader");
         Debug.Log (source1.name);
 
         sourceMask1 = source1.layer;
         Debug.Log (sourceMask1.value);
     }
     
     // Update is called once per frame
     void Update () {
         request ();
 
     }
 
     void request (){
 
         if (Input.GetMouseButtonDown (0)) {
 
             hitted ();
         }
     }
     public void hitted (){
         
         Ray ray = cam.ScreenPointToRay (Input.mousePosition);
         RaycastHit hit; 
 
         if (Physics.Raycast (ray, out hit, Mathf.Infinity, sourceMask1)) {
 
             Debug.Log ("Trader here!");
 
         }    else{
 
             Debug.Log("nothing here");
         }
     }
 }