diff --git a/core/modules/field/field.module b/core/modules/field/field.module
index 2044815..f497cec 100644
--- a/core/modules/field/field.module
+++ b/core/modules/field/field.module
@@ -372,11 +372,11 @@ function field_config_import_steps_alter(&$sync_steps, ConfigImporter $config_im
     $config_importer->getStorageComparer()->getSourceStorage()->read('core.extension'),
     $config_importer->getStorageComparer()->getChangelist('delete')
   );
-  if (count($fields)) {
+  if ($fields) {
     // Add a step to the beginning of the configuration synchronization process
     // to purge field data where the module that provides the field is being
     // uninstalled.
-    array_unshift($sync_steps, array('\Drupal\field\ConfigImporterFieldPurger', 'processDeletedFields'));
+    array_unshift($sync_steps, array('\Drupal\field\ConfigImporterFieldPurger', 'process'));
   };
 }
 
@@ -384,7 +384,7 @@ function field_config_import_steps_alter(&$sync_steps, ConfigImporter $config_im
  * Implements hook_form_FORM_ID_alter().
  *
  * Adds a warning if field data will be permanently removed by the configuration
- * synchronisation.
+ * synchronization.
  *
  * @see \Drupal\field\ConfigImporterFieldPurger
  */
@@ -396,9 +396,8 @@ function field_form_config_admin_import_form_alter(&$form, &$form_state) {
       $form_state['storage_comparer']->getSourceStorage()->read('core.extension'),
       $form_state['storage_comparer']->getChangelist('delete')
     );
-    if (count($fields)) {
-      // @todo improve message and don't use dsm.
-      drupal_set_message(t('Field data will be deleted by this synchronisation.'), 'warning');
+    if ($fields) {
+      drupal_set_message(t('Field data will be deleted by this synchronization.'), 'warning');
     }
   }
 }
diff --git a/core/modules/field/field.purge.inc b/core/modules/field/field.purge.inc
index 9d81a17..6a3347b 100644
--- a/core/modules/field/field.purge.inc
+++ b/core/modules/field/field.purge.inc
@@ -129,7 +129,7 @@ function field_purge_batch($batch_size, $field_uuid = NULL) {
   foreach ($deleted_fields as $field) {
     $field = new FieldConfig($field);
     if ($field_uuid && $field->uuid() != $field_uuid) {
-      // If a specific UUID provided only operate on that UUID.
+      // If a specific UUID is provided, only purge the corresponding field.
       continue;
     }
 
diff --git a/core/modules/field/lib/Drupal/field/ConfigImporterFieldPurger.php b/core/modules/field/lib/Drupal/field/ConfigImporterFieldPurger.php
index d88ce17..db3d8b9 100644
--- a/core/modules/field/lib/Drupal/field/ConfigImporterFieldPurger.php
+++ b/core/modules/field/lib/Drupal/field/ConfigImporterFieldPurger.php
@@ -9,24 +9,26 @@
 
 use Drupal\Core\Config\ConfigImporter;
 use Drupal\Core\Config\Entity\ConfigEntityStorage;
-use Drupal\Core\Config\StorageComparerInterface;
 
 /**
- * Processes field deletions before configuration synchronization.
+ * Processes field purges before a configuration synchronization.
  */
 class ConfigImporterFieldPurger {
 
   /**
-   * Processes deleted fields.
+   * Processes fields targeted for purge as part of a configuration sync.
+   *
+   * This takes care of deleting the field if necessary, and purging the data on
+   * the fly.
    *
    * @param array $context
    *   The batch context.
    * @param \Drupal\Core\Config\ConfigImporter $config_importer
    *   The config importer.
    */
-  public static function processDeletedFields(&$context, ConfigImporter $config_importer) {
+  public static function process(array &$context, ConfigImporter $config_importer) {
     if (!isset($context['sandbox']['field'])) {
-      static::calculateNumberOfBatchSteps($context, $config_importer);
+      static::initializeSandbox($context, $config_importer);
     }
 
     // Get the list of fields to purge.
@@ -54,23 +56,24 @@ public static function processDeletedFields(&$context, ConfigImporter $config_im
   }
 
   /**
-   * Calculates the number of steps necessary to purge all the field data.
+   * Initializes the batch context sandbox for processing field deletions.
+   *
+   * This calculates the number of steps necessary to purge all the field data
+   * and saves data for later use.
    *
    * @param array $context
    *   The batch context.
    * @param \Drupal\Core\Config\ConfigImporter $config_importer
    *   The config importer.
    */
-  protected static function calculateNumberOfBatchSteps(&$context, ConfigImporter $config_importer) {
-    // @todo should we use the staged batch size or the currently active?
+  protected static function initializeSandbox(array &$context, ConfigImporter $config_importer) {
     $context['sandbox']['field']['purge_batch_size'] = \Drupal::config('field.settings')->get('purge_batch_size');
     // Save the future list of installed extensions to limit the amount of times
     // the configuration is read from disk.
     $context['sandbox']['field']['extensions'] = $config_importer->getStorageComparer()->getSourceStorage()->read('core.extension');
 
+    $context['sandbox']['field']['steps_to_delete'] = 0;
     $fields = static::getFieldsToPurge($context['sandbox']['field']['extensions'], $config_importer->getUnprocessedConfiguration('delete'));
-    // There will be one step to delete the instances and field.
-    $context['sandbox']['field']['steps_to_delete'] = count($fields);
     foreach ($fields as $field) {
       $row_count = $field->entityCount();
       if ($row_count > 0) {
@@ -81,11 +84,15 @@ protected static function calculateNumberOfBatchSteps(&$context, ConfigImporter
         $context['sandbox']['field']['steps_to_delete'] += $how_many_steps;
       }
     }
+    // Each field needs one last field_purge_batch() call to remove the last
+    // instance and the field itself.
+    $context['sandbox']['field']['steps_to_delete'] += count($fields);
+
     $context['sandbox']['field']['current_progress'] = 0;
   }
 
   /**
-   * Gets the list of fields to purge before configuration synchronisation.
+   * Gets the list of fields to purge before configuration synchronization.
    *
    * If, during a configuration synchronization, a field is being deleted and
    * the module that provides the field type is being uninstalled then the field
@@ -97,12 +104,12 @@ protected static function calculateNumberOfBatchSteps(&$context, ConfigImporter
    *   The list of extensions that will be enabled after the configuration
    *   synchronization has finished.
    * @param array $deletes
-   *   The configuration that delete will be deleted by the configuration
-   *   synchronisation.
+   *   The configuration that will be deleted by the configuration
+   *   synchronization.
    *
    * @return \Drupal\field\Entity\FieldConfig[]
    *   An array of fields that need purging before configuration can be
-   *   synchronised.
+   *   synchronized.
    */
   public static function getFieldsToPurge(array $extensions, array $deletes) {
     $providers = array_keys($extensions['module']);
@@ -129,11 +136,12 @@ public static function getFieldsToPurge(array $extensions, array $deletes) {
 
     // Gather deleted fields from modules that are being uninstalled.
     $fields = entity_load_multiple_by_properties('field_config', array('deleted' => TRUE, 'include_deleted' => TRUE));
-    foreach($fields as $field) {
+    foreach ($fields as $field) {
       if (!in_array($field->module, $providers)) {
         $fields_to_delete[$field->id()] = $field;
       }
     }
     return $fields_to_delete;
   }
+
 }
diff --git a/core/modules/field/lib/Drupal/field/Tests/FieldImportDeleteUninstallTest.php b/core/modules/field/lib/Drupal/field/Tests/FieldImportDeleteUninstallTest.php
index bf7d4b0..102c525 100644
--- a/core/modules/field/lib/Drupal/field/Tests/FieldImportDeleteUninstallTest.php
+++ b/core/modules/field/lib/Drupal/field/Tests/FieldImportDeleteUninstallTest.php
@@ -25,7 +25,7 @@ class FieldImportDeleteUninstallTest extends FieldUnitTestBase {
   public static function getInfo() {
     return array(
       'name' => 'Field config delete and uninstall tests',
-      'description' => 'Delete field and instances during config synchronsiaton and uninstall module that provides the field type.',
+      'description' => 'Delete field and instances during config synchronization and uninstall module that provides the field type.',
       'group' => 'Field API',
     );
   }
@@ -105,7 +105,7 @@ public function testImportDeleteUninstall() {
     $staging->delete('field.instance.entity_test.entity_test.field_test');
 
     $steps = $this->configImporter()->initialize();
-    $this->assertIdentical($steps[0], array('\Drupal\field\ConfigImporterFieldPurger', 'processDeletedFields'), 'The additional processDeletedFields configuration synchronization step has been added.');
+    $this->assertIdentical($steps[0], array('\Drupal\field\ConfigImporterFieldPurger', 'process'), 'The additional process configuration synchronization step has been added.');
 
     $this->configImporter()->import();
 
@@ -120,7 +120,7 @@ public function testImportDeleteUninstall() {
   }
 
   /**
-   * Tests purging already fields and instances as part of config import.
+   * Tests purging already deleted fields and instances during a config import.
    */
   public function testImportAlreadyDeletedUninstall() {
     // Create a telephone field and instance for validation.
@@ -167,7 +167,7 @@ public function testImportAlreadyDeletedUninstall() {
     $this->assertTrue(isset($deleted_fields[$field_uuid]), 'Field has been deleted and needs purging before configuration synchronization.');
 
     $steps = $this->configImporter()->initialize();
-    $this->assertIdentical($steps[0], array('\Drupal\field\ConfigImporterFieldPurger', 'processDeletedFields'), 'The additional processDeletedFields configuration synchronization step has been added.');
+    $this->assertIdentical($steps[0], array('\Drupal\field\ConfigImporterFieldPurger', 'process'), 'The additional process configuration synchronization step has been added.');
 
     $this->configImporter()->import();
 
@@ -178,4 +178,5 @@ public function testImportAlreadyDeletedUninstall() {
     $deleted_fields = \Drupal::state()->get('field.field.deleted') ?: array();
     $this->assertFalse(isset($deleted_fields[$field_uuid]), 'Field has been completed removed from the system.');
   }
+
 }
diff --git a/core/modules/field/lib/Drupal/field/Tests/FieldImportDeleteUninstallUiTest.php b/core/modules/field/lib/Drupal/field/Tests/FieldImportDeleteUninstallUiTest.php
index 6f8ae71..2f33dee 100644
--- a/core/modules/field/lib/Drupal/field/Tests/FieldImportDeleteUninstallUiTest.php
+++ b/core/modules/field/lib/Drupal/field/Tests/FieldImportDeleteUninstallUiTest.php
@@ -26,7 +26,7 @@ class FieldImportDeleteUninstallUiTest extends FieldTestBase {
   public static function getInfo() {
     return array(
       'name' => 'Field config delete and uninstall UI tests',
-      'description' => 'Delete field and instances during config synchronsiaton and uninstall module that provides the field type through the UI.',
+      'description' => 'Delete field and instances during config synchronization and uninstall module that provides the field type through the UI.',
       'group' => 'Field API',
     );
   }
@@ -83,9 +83,9 @@ public function testImportDeleteUninstall() {
     $staging->delete('field.instance.entity_test.entity_test.field_test');
 
     $this->drupalGet('admin/config/development/configuration');
-    $this->assertText('Field data will be deleted by this synchronisation.');
+    $this->assertText('Field data will be deleted by this synchronization.');
     $this->drupalPostForm(NULL, array(), t('Import all'));
-    $this->assertNoText('Field data will be deleted by this synchronisation.');
+    $this->assertNoText('Field data will be deleted by this synchronization.');
     // This will purge all the data, delete the field and uninstall the
     // Telephone module.
     $this->rebuildContainer();