How to reset a form to pristine after submitted in Angular JS

I haven't the toughest time resetting this form to pristine once the reset/send button is clicked! I have tried the angular.copy method, $scope.contactForm.$setPristine(); to no avail. I was getting an error stating that $scope.contactForm.$setPristine(); was undefined. Do anyone see a problem in my code!

Here is my HTML

<!-- CONTACT FORM -->
<div class="sixteen columns contact-container">
    <h2>Contact Me</h2>
    <p class="required">* = Required</p>

    <div id="messages" data-ng-show="message">{{message}}</div>

    <form name="contactForm" id="contactForm" class="contact" method="post" novalidate>

        <label ng-class="{ 'has-error' : contactForm.name.$invalid && !contactForm.name.$pristine }">Name*
            <input type="text" name="name" class="form-control" data-ng-model="userData.name" placeholder="Joe Blow" required>
            <p data-ng-show="contactForm.name.$invalid && !contactForm.name.$pristine" class="help-block">You name is required.</p>
        </label>

        <label ng-class="{ 'has-error' : contactForm.email.$invalid && !contactForm.email.$pristine }">eMail*
            <input type="email" name="email" class="form-control" data-ng-model="userData.email" placeholder="joe84@email.com"     required>
            <p data-ng-show="contactForm.email.$invalid && !contactForm.email.$pristine" class="help-block">You email is required.    </p>
        </label>

        <label ng-class="{ 'has-error' : contactForm.comment.$invalid && !contactForm.comment.$pristine }">Comment*
            <textarea name="comment" class="form-control" ng-model="userData.comments" required></textarea>
            <p data-ng-show="contactForm.comment.$invalid && !contactForm.comment.$pristine" class="help-block">You comment is     required.</p>
        </label>

        <p>
            <button data-ng-click="reset()">Reset</button>
            <button type="submit" ng-click="processForm()">Submit</button>
        </p>
    </form>
</div>
<!-- END: CONTACT FORM -->

Here is my controller

 // 'use strict';
/* Controllers */
var myAppControllers = angular.module('myAppControllers', ['myServices']);

myAppControllers.controller('contactCtrl', ['$scope', '$http',
    function ($scope, $http, $compile) {
        console.log('contactCtrl');

        // Empty object to hold input info
        $scope.userData = {};

        // Process Form
        $scope.processForm = function () {
            $http({
                method: 'POST',
                url: 'send-mail.php',
                data: $.param($scope.userData),
                headers: {
                    'Content-Type': 'application/x-www-form-urlencoded'
                }
            })
                .success(function () {
                    $scope.userData = {};
                    alert('Message Sent');
                });
        }

        $scope.reset = function () {
            $scope.userData = {};
            console.log('Reset Clicked');
        }
    }
]);