diff --git a/lib/elements/array-selector.html b/lib/elements/array-selector.html
index af5ea9d02a..4f276c54e4 100644
--- a/lib/elements/array-selector.html
+++ b/lib/elements/array-selector.html
@@ -43,6 +43,7 @@
      * @constructor
      * @extends {superClass}
      * @implements {Polymer_ElementMixin}
+     * @private
      */
     let elementBase = Polymer.ElementMixin(superClass);
 
diff --git a/lib/legacy/class.html b/lib/legacy/class.html
index afe838cc57..135cdd9999 100644
--- a/lib/legacy/class.html
+++ b/lib/legacy/class.html
@@ -142,6 +142,7 @@
      */
     function GenerateClassFromInfo(info, Base) {
 
+      /** @private */
       class PolymerGenerated extends Base {
 
         static get properties() {
diff --git a/lib/legacy/legacy-element-mixin.html b/lib/legacy/legacy-element-mixin.html
index c1302b1346..afeb8bf017 100644
--- a/lib/legacy/legacy-element-mixin.html
+++ b/lib/legacy/legacy-element-mixin.html
@@ -48,6 +48,7 @@
      * @implements {Polymer_ElementMixin}
      * @implements {Polymer_GestureEventListeners}
      * @implements {Polymer_DirMixin}
+     * @private
      */
     const legacyElementBase = Polymer.DirMixin(Polymer.GestureEventListeners(Polymer.ElementMixin(base)));
 
diff --git a/lib/mixins/dir-mixin.html b/lib/mixins/dir-mixin.html
index 68db35d5fe..c029ed3e37 100644
--- a/lib/mixins/dir-mixin.html
+++ b/lib/mixins/dir-mixin.html
@@ -90,6 +90,7 @@
        * @constructor
        * @extends {base}
        * @implements {Polymer_PropertyAccessors}
+       * @private
        */
       const elementBase = Polymer.PropertyAccessors(base);
 
diff --git a/lib/mixins/disable-upgrade-mixin.html b/lib/mixins/disable-upgrade-mixin.html
index f714325de5..e38841ae00 100644
--- a/lib/mixins/disable-upgrade-mixin.html
+++ b/lib/mixins/disable-upgrade-mixin.html
@@ -45,8 +45,10 @@
      * @constructor
      * @extends {base}
      * @implements {Polymer_ElementMixin}
+     * @private
      */
     const superClass = Polymer.ElementMixin(base);
+
     /**
      * @polymer
      * @mixinClass
diff --git a/lib/mixins/element-mixin.html b/lib/mixins/element-mixin.html
index b0f7fba988..f14c7ffb95 100644
--- a/lib/mixins/element-mixin.html
+++ b/lib/mixins/element-mixin.html
@@ -98,6 +98,7 @@
      * @extends {base}
      * @implements {Polymer_PropertyEffects}
      * @implements {Polymer_PropertiesMixin}
+     * @private
      */
     const polymerElementBase = Polymer.PropertiesMixin(Polymer.PropertyEffects(base));
 
diff --git a/lib/mixins/properties-mixin.html b/lib/mixins/properties-mixin.html
index 782311bb8e..7ee3e86952 100644
--- a/lib/mixins/properties-mixin.html
+++ b/lib/mixins/properties-mixin.html
@@ -58,6 +58,7 @@
      * @constructor
      * @extends {superClass}
      * @implements {Polymer_PropertiesChanged}
+     * @private
      */
     const base = Polymer.PropertiesChanged(superClass);
 
diff --git a/lib/mixins/property-accessors.html b/lib/mixins/property-accessors.html
index f26f467b12..a6b165c92d 100644
--- a/lib/mixins/property-accessors.html
+++ b/lib/mixins/property-accessors.html
@@ -105,6 +105,7 @@
      * @extends {superClass}
      * @implements {Polymer_PropertiesChanged}
      * @unrestricted
+     * @private
      */
      const base = Polymer.PropertiesChanged(superClass);
 
diff --git a/lib/mixins/property-effects.html b/lib/mixins/property-effects.html
index de92b17c4a..5cb13c7233 100644
--- a/lib/mixins/property-effects.html
+++ b/lib/mixins/property-effects.html
@@ -1122,6 +1122,7 @@
      * @implements {Polymer_PropertyAccessors}
      * @implements {Polymer_TemplateStamp}
      * @unrestricted
+     * @private
      */
     const propertyEffectsBase = Polymer.TemplateStamp(Polymer.PropertyAccessors(superClass));
 
diff --git a/lib/mixins/strict-binding-parser.html b/lib/mixins/strict-binding-parser.html
index 03a3b3d278..ec33b1c39e 100644
--- a/lib/mixins/strict-binding-parser.html
+++ b/lib/mixins/strict-binding-parser.html
@@ -126,6 +126,7 @@
      * @constructor
      * @extends {base}
      * @implements {Polymer_PropertyEffects}
+     * @private
      */
     const elementBase = Polymer.PropertyEffects(base);
 
diff --git a/lib/utils/mixin.html b/lib/utils/mixin.html
index e97b3e2123..17e1789082 100644
--- a/lib/utils/mixin.html
+++ b/lib/utils/mixin.html
@@ -22,6 +22,7 @@
   /**
    * @constructor
    * @extends {Function}
+   * @private
    */
   function MixinFunction(){}
   /** @type {(WeakMap | undefined)} */
diff --git a/lib/utils/templatize.html b/lib/utils/templatize.html
index 67b4a53179..85c59a1706 100644
--- a/lib/utils/templatize.html
+++ b/lib/utils/templatize.html
@@ -21,9 +21,11 @@
     // class only because Babel (incorrectly) requires super() in the class
     // constructor even though no `this` is used and it returns an instance.
     let newInstance = null;
+
     /**
      * @constructor
      * @extends {HTMLTemplateElement}
+     * @private
      */
     function HTMLTemplateElementExtension() { return newInstance; }
     HTMLTemplateElementExtension.prototype = Object.create(HTMLTemplateElement.prototype, {
@@ -32,16 +34,20 @@
         writable: true
       }
     });
+
     /**
      * @constructor
      * @implements {Polymer_PropertyEffects}
      * @extends {HTMLTemplateElementExtension}
+     * @private
      */
     const DataTemplate = Polymer.PropertyEffects(HTMLTemplateElementExtension);
+
     /**
      * @constructor
      * @implements {Polymer_MutableData}
      * @extends {DataTemplate}
+     * @private
      */
     const MutableDataTemplate = Polymer.MutableData(DataTemplate);
 
@@ -53,8 +59,8 @@
       newInstance = null;
     }
 
-    // Base class for TemplateInstance's
     /**
+     * Base class for TemplateInstance.
      * @constructor
      * @implements {Polymer_PropertyEffects}
      */
@@ -268,6 +274,7 @@
      * @constructor
      * @extends {TemplateInstanceBase}
      * @implements {Polymer_MutableData}
+     * @private
      */
     const MutableTemplateInstanceBase = Polymer.MutableData(TemplateInstanceBase);
 
@@ -311,6 +318,7 @@
         let klass = templateInfo.templatizeTemplateClass;
         if (!klass) {
           let base = options.mutableData ? MutableDataTemplate : DataTemplate;
+          /** @private */
           klass = templateInfo.templatizeTemplateClass =
             class TemplatizedTemplate extends base {};
           // Add template - >instances effects
diff --git a/polymer-element.html b/polymer-element.html
index aeb4a0e193..3291f1754e 100644
--- a/polymer-element.html
+++ b/polymer-element.html
@@ -20,25 +20,18 @@
    * and property change observation.
    *
    * @customElement
-   * @polymer
    * @memberof Polymer
    * @constructor
    * @implements {Polymer_ElementMixin}
-   * @extends HTMLElement
+   * @extends {HTMLElement}
    * @appliesMixin Polymer.ElementMixin
    * @summary Custom element base class that provides the core API for Polymer's
    *   key meta-programming features including template stamping, data-binding,
    *   attribute deserialization, and property change observation
    */
-  const Element = Polymer.ElementMixin(HTMLElement);
-  /**
-   * @constructor
-   * @implements {Polymer_ElementMixin}
-   * @extends {HTMLElement}
-   */
-  Polymer.Element = Element;
+  Polymer.Element = Polymer.ElementMixin(HTMLElement);
 
   // NOTE: this is here for modulizer to export `html` for the module version of this file
   Polymer.html = Polymer.html;
 })();
-</script>
\ No newline at end of file
+</script>