diff --git a/scrapy/newitem/loader/__init__.py b/scrapy/newitem/loader/__init__.py
index 1ab0fb476..09640aabb 100644
--- a/scrapy/newitem/loader/__init__.py
+++ b/scrapy/newitem/loader/__init__.py
@@ -11,10 +11,10 @@ class ItemLoader(object):
     default_expander = IdentityExpander()
     default_reducer = TakeFirst()
 
-    def __init__(self, **loader_args):
-        if 'item' not in loader_args:
-            loader_args['item'] = self.default_item_class()
-        self._item = loader_args['item']
+    def __init__(self, item=None, **loader_args):
+        if not item:
+            item = self.default_item_class()
+        self._item = loader_args['item'] = item
         self._loader_args = loader_args
         self._values = defaultdict(list)
 
diff --git a/scrapy/newitem/loader/expanders.py b/scrapy/newitem/loader/expanders.py
index 33fc0f833..3e2cb68d4 100644
--- a/scrapy/newitem/loader/expanders.py
+++ b/scrapy/newitem/loader/expanders.py
@@ -1,5 +1,7 @@
 """
-This module provides some commonly used Expanders
+This module provides some commonly used Expanders.
+
+See documentation in docs/topics/newitem-loader.rst
 """
 
 from scrapy.utils.misc import arg_to_iter
@@ -7,19 +9,6 @@ from scrapy.utils.python import get_func_args
 from scrapy.utils.datatypes import MergeDict
 
 class TreeExpander(object):
-    """An expander which applies the given list of functions consecutively to
-    each value returned by the previous function.
-
-    The algorithm consists in an ordered list of functions, each of which
-    receives one value and can return zero, one or more values (as a list or
-    iterable). If a function returns more than one value, the next function in
-    the list will be called with each of those values, potentially returning
-    more values and thus expanding the execution into different branches, which
-    is why this expander is called Tree Expander.
-    
-    The expander functions can optionally receive a ``loader_args`` argument,
-    which will contain the current active loader arguments.
-    """
 
     def __init__(self, *functions, **default_loader_args):
         self.default_loader_args = default_loader_args
@@ -51,9 +40,6 @@ class TreeExpander(object):
 
 
 class IdentityExpander(object):
-    """An expander which returns the original values unchanged. It doesn't
-    support any constructor arguments.
-    """
 
     def __call__(self, values, loader_args):
         return arg_to_iter(values)
diff --git a/scrapy/newitem/loader/reducers.py b/scrapy/newitem/loader/reducers.py
index 76ba754b4..8f9a3cc9b 100644
--- a/scrapy/newitem/loader/reducers.py
+++ b/scrapy/newitem/loader/reducers.py
@@ -1,9 +1,10 @@
 """
-This module provides some commonly used Reducers
+This module provides some commonly used Reducers.
+
+See documentation in docs/topics/newitem-loader.rst
 """
 
 class TakeFirst(object):
-    """Return the first non-null value from the list to reduce"""
 
     def __call__(self, values):
         for value in values:
@@ -12,19 +13,12 @@ class TakeFirst(object):
 
 
 class Identity(object):
-    """Return the list to reduce untouched"""
 
     def __call__(self, values):
         return values
 
 
-class JoinStrings(object):
-    """Return a string with the contents of the list to reduce joined with the
-    separator given in the constructor, which defaults to u' '. 
-
-    When using the default separator, this reducer is equivalent to the
-    function: u' '.join 
-    """
+class Join(object):
 
     def __init__(self, separator=u' '):
         self.separator = separator
diff --git a/scrapy/tests/test_itemloader.py b/scrapy/tests/test_itemloader.py
index 9dd949e8d..de0b1fb67 100644
--- a/scrapy/tests/test_itemloader.py
+++ b/scrapy/tests/test_itemloader.py
@@ -2,7 +2,7 @@ import unittest
 
 from scrapy.newitem.loader import ItemLoader
 from scrapy.newitem.loader.expanders import TreeExpander, IdentityExpander
-from scrapy.newitem.loader.reducers import JoinStrings, Identity
+from scrapy.newitem.loader.reducers import Join, Identity
 from scrapy.newitem import Item, Field
 
 # test items
@@ -161,14 +161,14 @@ class ItemLoaderTest(unittest.TestCase):
         self.assertEqual(il.get_reduced_value('name'), u'Mar')
 
         class TakeFirstItemLoader(TestItemLoader):
-            name_red = JoinStrings()
+            name_red = Join()
 
         il = TakeFirstItemLoader()
         il.add_value('name', [u'mar', u'ta'])
         self.assertEqual(il.get_reduced_value('name'), u'Mar Ta')
 
         class TakeFirstItemLoader(TestItemLoader):
-            name_red = JoinStrings("<br>")
+            name_red = Join("<br>")
 
         il = TakeFirstItemLoader()
         il.add_value('name', [u'mar', u'ta'])