diff --git a/.gitignore b/.gitignore
index de4a392..c606205 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 /vendor
 /composer.lock
+/doc/coverage
diff --git a/phpunit.xml b/phpunit.xml
index ad9b759..c48c5d8 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -2,8 +2,8 @@
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/7.5/phpunit.xsd"
          bootstrap="vendor/autoload.php"
-         forceCoversAnnotation="true"
-         beStrictAboutCoversAnnotation="true"
+         forceCoversAnnotation="false"
+         beStrictAboutCoversAnnotation="false"
          beStrictAboutOutputDuringTests="true"
          beStrictAboutTodoAnnotatedTests="true"
          verbose="true">
diff --git a/src/Ingredient/Base.php b/src/Ingredient/Base.php
index 85f647d..475e686 100644
--- a/src/Ingredient/Base.php
+++ b/src/Ingredient/Base.php
@@ -35,6 +35,13 @@ class Base
         return $this->components;
     }
 
+    public function getComponentPercent(string $component): float
+    {
+        return array_key_exists($component, $this->components)
+            ? $this->components[$component]
+            : 0;
+    }
+
     public static function parseComponents(string $base)
     {
         $found = [];
diff --git a/src/Ingredient/Ingredient.php b/src/Ingredient/Ingredient.php
index cc7f82b..29ed22d 100644
--- a/src/Ingredient/Ingredient.php
+++ b/src/Ingredient/Ingredient.php
@@ -12,6 +12,14 @@ class Ingredient implements IngredientInterface
 
     protected $base;
 
+    /**
+     * Ingredient constructor
+     * 
+     * @param string The name of the ingredient
+     * @param string|null The brand of the ingredient
+     * @param float Percent
+     * @param string The base mix (Default PG100)
+     */
     public function __construct(string $name, ?string $brand=null, float $percent=0.0, string $base="PG100")
     {
         $this->name = $name;
@@ -52,4 +60,12 @@ class Ingredient implements IngredientInterface
         return $this->base;
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    public function getSpecificGravity(): ?float
+    {
+        return null;
+    }
+
 }
\ No newline at end of file
diff --git a/src/Ingredient/IngredientInterface.php b/src/Ingredient/IngredientInterface.php
index edf3460..b68b6a4 100644
--- a/src/Ingredient/IngredientInterface.php
+++ b/src/Ingredient/IngredientInterface.php
@@ -34,4 +34,11 @@ interface IngredientInterface
      */
     public function getBase(): ?string;
 
+    /**
+     * Return the ASG in g/mL for the specific flavor, or null if not available.
+     * 
+     * @return float|null
+     */
+    public function getSpecificGravity(): ?float;
+
 }
\ No newline at end of file
diff --git a/src/Ingredient/NicotineBase.php b/src/Ingredient/NicotineBase.php
index acb6ea4..38b7937 100644
--- a/src/Ingredient/NicotineBase.php
+++ b/src/Ingredient/NicotineBase.php
@@ -5,19 +5,49 @@ namespace NoccyLabs\Juicer\Ingredient;
 class NicotineBase
 {
 
+    const MASS_NICOTINE = 1.01;
+
     protected $base;
 
     protected $strength;
 
+    /**
+     * NicotineBase constructor
+     * 
+     * @param Base The base mix of the nicotine base
+     * @param int The strength of the nic base (eg. 18)
+     */
     public function __construct(Base $base, int $strength)
     {
         $this->base = $base;
-        $this->nicotineStrength = $strength;
+        $this->strength = $strength;
     }
 
+    /**
+     * Get the Apparent Specific Gravity of the nicotine mixture taking
+     * in account the base mix and nicotine strength.
+     * 
+     * @return float
+     */
     public function getSpecificGravity(): float
     {
-        return 0.0; 
+
+        // 18mg/ml is 1.8% nicotine
+        $nicotinePercent = $this->strength / 1000;
+
+        // Figure out how much the remaining percent is
+        $baseRemain = 1.0 - $nicotinePercent;
+
+        $base = $this->base->getComponents();
+        $remainVg = $baseRemain * ($base['VG'] / 100);
+        $remainPg = $baseRemain * ($base['PG'] / 100);
+
+        $sgNic = $nicotinePercent * self::MASS_NICOTINE;
+        $sgVg = $remainVg * Base::MASS_VG;
+        $sgPg = $remainPg * Base::MASS_PG;
+
+        return $sgNic + $sgVg + $sgPg;
+
     }
 
 }
diff --git a/src/Recipe/Importer/JsonImporter.php b/src/Recipe/Importer/JsonImporter.php
index 4435530..0a5a61c 100644
--- a/src/Recipe/Importer/JsonImporter.php
+++ b/src/Recipe/Importer/JsonImporter.php
@@ -3,18 +3,26 @@
 namespace NoccyLabs\Juicer\Recipe\Importer;
 
 use NoccyLabs\Juicer\Recipe\RecipeInterface;
-use NoccyLabs\Juicer\Ingredient\IngredientInterface;
 use NoccyLabs\Juicer\Recipe\Recipe;
 use NoccyLabs\Juicer\Ingredient\Ingredient;
 
+/**
+ * Import recipes from Json
+ * 
+ */
 class JsonImporter
 {
 
+    /**
+     * Import a recipe from json
+     * 
+     * @param string The json string to parse and import
+     * @return RecipeInterface
+     */
     public function import(string $json): RecipeInterface
     {
         $data = json_decode($json);
 
-
         $recipe = new Recipe();
         $recipe->setRecipeName(@$data->recipe);
         $recipe->setRecipeAuthor(@$data->author);
@@ -29,6 +37,12 @@ class JsonImporter
         return $recipe;
     }
 
+    /**
+     * Import a recipe from json contained in a file
+     * 
+     * @param string The filename to read and import
+     * @return RecipeInterface
+     */
     public function readFromFile(string $filename): RecipeInterface
     {
         $fd = fopen($filename, "r");
diff --git a/src/Recipe/Mixer/MeasuredIngredient.php b/src/Recipe/Mixer/MeasuredIngredient.php
index f25d4e8..1da1e20 100644
--- a/src/Recipe/Mixer/MeasuredIngredient.php
+++ b/src/Recipe/Mixer/MeasuredIngredient.php
@@ -22,47 +22,96 @@ class MeasuredIngredient implements IngredientInterface
     /** @var float Weight in grams (g) */
     protected $weight;
 
-    public function __construct(string $name, ?string $brand, string $base, float $asg, float $percent, float $volume)
+    /**
+     * MeasuredIngredient constructor
+     * 
+     * @param IngredientInterface|string The ingredient 
+     * @param float The percent of the ingredient to use
+     * @param float The volume of the ingredient to mix (in mL)
+     * @param string The base of the ingredient, override any set on ingredient
+     */
+    public function __construct($ingredient, float $percent, float $volume, string $base=null)
     {
-        $this->name = $name;
-        $this->brand = $brand;
-        $this->base = $base;
+        if ($ingredient instanceof IngredientInterface) {
+            $asg = $ingredient->getSpecificGravity();
+            $this->name = $ingredient->getFlavorName();
+            $this->brand = $ingredient->getFlavorBrand();
+            $this->base = $base??$ingredient->getBase();
+        } else {
+            $asg = null;
+            $this->name = $ingredient;
+            $this->base = $base??"PG100";
+        }
+
+        if (!$asg) {
+            $base = new Base($this->base);
+            $asg = $base->getSpecificGravity();
+        }
+
         $this->asg = $asg;
         $this->percent = $percent;
         $this->volume = $volume;
         $this->weight = $volume * $asg;
     }
 
+    /**
+     * 
+     * @return string
+     */
     public function getFlavorName(): string
     {
         return $this->name;
     }
 
+    /**
+     * 
+     * @return string|null
+     */
     public function getFlavorBrand(): ?string
     {
         return $this->brand;
     }
 
+    /**
+     * 
+     * @return string|null
+     */
     public function getBase(): ?string
     {
         return $this->base;
     }
 
+    /**
+     * 
+     * @return float
+     */
     public function getPercent(): float
     {
         return $this->percent;
     }
 
+    /**
+     * 
+     * @return float
+     */
     public function getSpecificGravity(): float
     {
         return $this->asg;
     }
 
+    /**
+     * 
+     * @return float
+     */
     public function getVolume(): float
     {
         return $this->volume;
     }
 
+    /**
+     * 
+     * @return float
+     */
     public function getWeight(): float
     {
         return $this->weight;
diff --git a/src/Recipe/Mixer/MeasuredRecipe.php b/src/Recipe/Mixer/MeasuredRecipe.php
new file mode 100644
index 0000000..e74221c
--- /dev/null
+++ b/src/Recipe/Mixer/MeasuredRecipe.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace NoccyLabs\Juicer\Recipe\Mixer;
+
+use NoccyLabs\Juicer\Ingredient\Base;
+use NoccyLabs\Juicer\Recipe\RecipeInterface;
+
+class MeasuredRecipe
+{
+
+    public function __construct(RecipeInterface $recipe, array $mixedIngredients)
+    {
+
+    }
+
+
+    public function getTotalFlavorMl()
+    {
+
+    }
+
+    public function getTotalFlavorPercent()
+    {
+
+    }
+
+    public function getTotalFlavorGrams()
+    {
+
+    }
+}
\ No newline at end of file
diff --git a/src/Recipe/Mixer/Mixer.php b/src/Recipe/Mixer/Mixer.php
index 8c656d9..f833b07 100644
--- a/src/Recipe/Mixer/Mixer.php
+++ b/src/Recipe/Mixer/Mixer.php
@@ -12,17 +12,47 @@ class Mixer
 
     public function mixRecipe(RecipeInterface $recipe, int $volume, Base $base, int $nicotineStrength, ?NicotineBase $nicotineBase=null)
     {
+        // Array holding our final list
         $mixed = [];
 
+        $targetVg = 0;
+        $targetPg = 0;
 
         $components = $base->getComponents();
         
         if (array_key_exists('VG', $components) && $components['VG'] > 0) {
-            $mixed[] = new MeasuredIngredient("VG", null, "VG100", Base::MASS_VG, 100, $volume);
+            $targetVg = $components['VG'];
         }
 
         if (array_key_exists('PG', $components) && $components['PG'] > 0) {
-            $mixed[] = new MeasuredIngredient("PG", null, "PG100", Base::MASS_PG, 100, $volume);
+            $targetPg = $components['PG'];
+        }
+
+        $addedVg = 0;
+        $addedPg = 0;
+
+        foreach ($recipe->getIngredients() as $ingredient) {
+            $ingredientBase = new Base($ingredient->getBase());
+            $ingredientPercent = $ingredient->getPercent();
+            $floatPercent = $ingredientPercent / 100;
+            $addedVg += $floatPercent * $ingredientBase->getComponentPercent('VG');
+            $addedPg += $floatPercent * $ingredientBase->getComponentPercent('PG');
+        }
+
+        if ($targetVg > $addedVg) {
+            $remainingVg = max(0, $targetVg - $addedVg);
+            $mixed[] = new MeasuredIngredient("VG", $remainingVg, $volume * ($remainingVg/100), "VG100");
+        }
+        if ($targetPg > $addedPg) {
+            $remainingPg = max(0, $targetPg - $addedPg);
+            $mixed[] = new MeasuredIngredient("PG", $remainingPg, $volume * ($remainingPg/100), "PG100");
+        }
+
+        foreach ($recipe->getIngredients() as $ingredient) {
+            $ingredientBase = new Base($ingredient->getBase());
+            $ingredientPercent = $ingredient->getPercent();
+            $floatPercent = $ingredientPercent / 100;
+            $mixed[] = new MeasuredIngredient($ingredient, $ingredientPercent, $volume * $floatPercent);
         }
 
         return $mixed;
diff --git a/tests/Ingredient/NicotineBaseTest.php b/tests/Ingredient/NicotineBaseTest.php
new file mode 100644
index 0000000..e5662bc
--- /dev/null
+++ b/tests/Ingredient/NicotineBaseTest.php
@@ -0,0 +1,35 @@
+<?php
+
+namespace NoccyLabs\Juicer\Ingredient;
+
+
+class NicotineBaseTest extends \PhpUnit\Framework\TestCase
+{
+    public function getNicotineAsgData()
+    {
+        return [
+            [ 'PG100', 100, 1.035 ],
+            [ 'PG100', 60, 1.03632 ],
+            [ 'PG100', 50, 1.0366 ],
+            [ 'PG100', 48, 1.036656 ],
+            [ 'PG100', 36, 1.036992 ],
+            [ 'PG100', 24, 1.037328 ],
+            [ 'VG100', 100, 1.235 ],
+            [ 'VG100', 60, 1.245 ],
+            [ 'VG100', 50, 1.2475 ],
+            [ 'VG100', 48, 1.248 ],
+            [ 'VG100', 36, 1.251 ],
+            [ 'VG100', 24, 1.254 ],
+        ];
+    }
+
+    /**
+     * @dataProvider getNicotineAsgData
+     */
+    public function testThatTheApparentSpecificGravityIsCorect($base, $strength, $expected)
+    {
+        $nic = new NicotineBase(new Base($base), $strength);
+        $this->assertEquals(round($expected,3), round($nic->getSpecificGravity(),3));
+    }
+
+}
diff --git a/tests/Recipe/Importer/JsonImporterTest.php b/tests/Recipe/Importer/JsonImporterTest.php
index b7fbab7..c15f9da 100644
--- a/tests/Recipe/Importer/JsonImporterTest.php
+++ b/tests/Recipe/Importer/JsonImporterTest.php
@@ -5,6 +5,7 @@ namespace NoccyLabs\Juicer\Recipe\Importer;
 use NoccyLabs\Juicer\Recipe\Recipe;
 use NoccyLabs\Juicer\Ingredient\Ingredient;
 use NoccyLabs\Juicer\Recipe\Exporter\JsonExporter;
+use NoccyLabs\Juicer\Recipe\RecipeInterface;
 
 class JsonImporterTest extends \PhpUnit\Framework\TestCase
 {
@@ -41,5 +42,14 @@ class JsonImporterTest extends \PhpUnit\Framework\TestCase
         $this->assertEquals($recipe, $importedRecipe);
     }
 
+    public function testThatRecipesCanBeImportedFromFile()
+    {
+
+        $importer = new JsonImporter();
+        $importedRecipe = $importer->readFromFile(__DIR__."/../../data/recipe1.json");
+
+        $this->assertInstanceOf(RecipeInterface::class, $importedRecipe);
+        $this->assertEquals("Recipe 1", $importedRecipe->getRecipeName());
+    }
 
 }
\ No newline at end of file
diff --git a/tests/Recipe/Mixer/MixerTest.php b/tests/Recipe/Mixer/MixerTest.php
index 4bded74..81678a9 100644
--- a/tests/Recipe/Mixer/MixerTest.php
+++ b/tests/Recipe/Mixer/MixerTest.php
@@ -5,55 +5,74 @@ namespace NoccyLabs\Juicer\Recipe\Mixer;
 use NoccyLabs\Juicer\Recipe\Recipe;
 use NoccyLabs\Juicer\Ingredient\Ingredient;
 use NoccyLabs\Juicer\Ingredient\Base;
+use NoccyLabs\Juicer\Recipe\RecipeInterface;
 
 class MixerTest extends \PhpUnit\Framework\TestCase
 {
-    public function testMixingEmptyRecipesWithVg()
+
+    public function getDataForEmptyRecipes()
     {
-        $recipe = new Recipe();
-        $mixer = new Mixer();
-
-        $base = new Base("VG100");
-        $mixed = $mixer->mixRecipe($recipe, 10, $base, 0);
-
-        $this->assertCount(1, $mixed);
-        $mixedVg = reset($mixed);
-
-        $this->assertEquals(10, $mixedVg->getVolume());
-        $this->assertEquals("VG", $mixedVg->getFlavorName());
+        return [
+            [ 'VG100', 10, [ 'VG' => 10 ], 10 ],
+            [ 'PG100', 10, [ 'PG' => 10 ], 10 ],
+            [ 'VG70', 10, [ 'VG' => 7, 'PG' => 3 ], 10 ],
+            [ 'VG50', 10, [ 'VG' => 5, 'PG' => 5 ], 10 ]
+        ];
     }
 
-    public function testMixingEmptyRecipesWithPg()
+    /**
+     * @dataProvider getDataForEmptyRecipes
+     */
+    public function testMixingEmptyRecipes($base, $amount, array $assertBases, $assertAmount)
     {
         $recipe = new Recipe();
         $mixer = new Mixer();
 
-        $base = new Base("PG100");
-        $mixed = $mixer->mixRecipe($recipe, 10, $base, 0);
+        $base = new Base($base);
+        $mixed = $mixer->mixRecipe($recipe, $amount, $base, 0);
 
-        $this->assertCount(1, $mixed);
-        $mixedPg = reset($mixed);
-
-        $this->assertEquals(10, $mixedPg->getVolume());
-        $this->assertEquals("PG", $mixedPg->getFlavorName());
+        $this->assertCount(count($assertBases), $mixed);
+        $mixedAmount = 0;
+        foreach ($mixed as $measured) {
+            $name = $measured->getFlavorName();
+            if (!array_key_exists($name, $assertBases)) {
+                $this->assertFail("Mixed contains unexpected ingredients");
+            }
+            $mixedAmount += $measured->getVolume();
+        }
+        $this->assertEquals($assertAmount, $mixedAmount);
     }
 
-    public function testMixingEmptyRecipesWith70Vg30Pg()
+    public function getDataForDummyRecipes()
+    {
+        $ingredientA1 = new Ingredient("Ingredient A1", null, 2);
+        $ingredientA2 = new Ingredient("Ingredient A2", null, 3);
+        $recipeA = new Recipe();
+        $recipeA->setRecipeName("Recipe A");
+        $recipeA->addIngredient($ingredientA1);
+        $recipeA->addIngredient($ingredientA2);
+        return [
+            [ $recipeA, 'VG70', 10 ],
+        ];
+    }
+
+    /**
+     * @dataProvider getDataForDummyRecipes
+     */
+    public function testMixingDummyRecipes(RecipeInterface $recipe, $base, $amount)
     {
-        $recipe = new Recipe();
         $mixer = new Mixer();
+        $base = new Base($base);
+        $mixed = $mixer->mixRecipe($recipe, $amount, $base, 0);
 
-        $base = new Base("VG70");
-        $mixed = $mixer->mixRecipe($recipe, 10, $base, 0);
+        $expectedCount = count($base->getComponents()) + count($recipe->getIngredients());
 
-        $this->assertCount(2, $mixed);
-
-        $mixedVg = array_shift($mixed);
-        $this->assertEquals(10, $mixedVg->getVolume());
-        $this->assertEquals("VG", $mixedVg->getFlavorName());
-        $mixedPg = array_shift($mixed);
-        $this->assertEquals(10, $mixedPg->getVolume());
-        $this->assertEquals("PG", $mixedPg->getFlavorName());
+        $this->assertCount($expectedCount, $mixed);
+        $mixedAmount = 0;
+        foreach ($mixed as $measured) {
+            $mixedAmount += $measured->getVolume();
+        }
+        $this->assertEquals($amount, $mixedAmount);
     }
 
 }
\ No newline at end of file
diff --git a/tests/data/recipe1.json b/tests/data/recipe1.json
new file mode 100644
index 0000000..2e1130a
--- /dev/null
+++ b/tests/data/recipe1.json
@@ -0,0 +1,9 @@
+{
+    "recipe": "Recipe 1",
+    "author": "Noccy",
+    "tags": [ "foo", "bar" ],
+    "ingredients": [
+        { "flavor":"Flavor A", "brand":"Brand A", "percent":3 },
+        { "flavor":"Flavor B", "brand":"Brand B", "percent":2 }
+    ]
+}