diff --git a/python/damask/_grid.py b/python/damask/_grid.py
index 53b0bd5dc..94f7eefd0 100644
--- a/python/damask/_grid.py
+++ b/python/damask/_grid.py
@@ -70,7 +70,7 @@ class Grid:
               ])
 
 
-    def __copy__(self) -> "Grid":
+    def __copy__(self) -> 'Grid':
         """Create deep copy."""
         return copy.deepcopy(self)
 
@@ -161,7 +161,7 @@ class Grid:
 
 
     @staticmethod
-    def load(fname: Union[str, Path]) -> "Grid":
+    def load(fname: Union[str, Path]) -> 'Grid':
         """
         Load from VTK image data file.
 
@@ -190,7 +190,7 @@ class Grid:
 
     @typing. no_type_check
     @staticmethod
-    def load_ASCII(fname)-> "Grid":
+    def load_ASCII(fname)-> 'Grid':
         """
         Load from geom file.
 
@@ -264,7 +264,7 @@ class Grid:
 
 
     @staticmethod
-    def load_Neper(fname: Union[str, Path]) -> "Grid":
+    def load_Neper(fname: Union[str, Path]) -> 'Grid':
         """
         Load from Neper VTK file.
 
@@ -279,7 +279,7 @@ class Grid:
             Grid-based geometry from file.
 
         """
-        v = VTK.load(fname,'vtkImageData')
+        v = VTK.load(fname,'ImageData')
         cells = np.array(v.vtk_data.GetDimensions())-1
         bbox  = np.array(v.vtk_data.GetBounds()).reshape(3,2).T
 
@@ -292,7 +292,7 @@ class Grid:
     def load_DREAM3D(fname: Union[str, Path],
                      feature_IDs: str = None, cell_data: str = None,
                      phases: str = 'Phases', Euler_angles: str = 'EulerAngles',
-                     base_group: str = None) -> "Grid":
+                     base_group: str = None) -> 'Grid':
         """
         Load DREAM.3D (HDF5) file.
 
@@ -354,7 +354,7 @@ class Grid:
     @staticmethod
     def from_table(table: Table,
                    coordinates: str,
-                   labels: Union[str, Sequence[str]]) -> "Grid":
+                   labels: Union[str, Sequence[str]]) -> 'Grid':
         """
         Create grid from ASCII table.
 
@@ -453,7 +453,7 @@ class Grid:
                                   size: FloatSequence,
                                   seeds: np.ndarray,
                                   material: IntSequence = None,
-                                  periodic: bool = True) -> "Grid":
+                                  periodic: bool = True) -> 'Grid':
         """
         Create grid from Voronoi tessellation.
 
@@ -539,7 +539,7 @@ class Grid:
                              surface: str,
                              threshold: float = 0.0,
                              periods: int = 1,
-                             materials: IntSequence = (0,1)) -> "Grid":
+                             materials: IntSequence = (0,1)) -> 'Grid':
         """
         Create grid from definition of triply periodic minimal surface.
 
@@ -685,7 +685,7 @@ class Grid:
                       fill: int = None,
                       R: Rotation = Rotation(),
                       inverse: bool = False,
-                      periodic: bool = True) -> "Grid":
+                      periodic: bool = True) -> 'Grid':
         """
         Insert a primitive geometric object at a given position.
 
@@ -770,7 +770,7 @@ class Grid:
                    )
 
 
-    def mirror(self, directions: Sequence[str], reflect: bool = False) -> "Grid":
+    def mirror(self, directions: Sequence[str], reflect: bool = False) -> 'Grid':
         """
         Mirror grid along given directions.
 
@@ -822,7 +822,7 @@ class Grid:
                    )
 
 
-    def flip(self, directions: Union[Literal['x', 'y', 'z'], Sequence[Literal['x', 'y', 'z']]]) -> "Grid":
+    def flip(self, directions: Union[Literal['x', 'y', 'z'], Sequence[Literal['x', 'y', 'z']]]) -> 'Grid':
         """
         Flip grid along given directions.
 
@@ -852,7 +852,7 @@ class Grid:
                    )
 
 
-    def scale(self, cells: IntSequence, periodic: bool = True) -> "Grid":
+    def scale(self, cells: IntSequence, periodic: bool = True) -> 'Grid':
         """
         Scale grid to new cells.
 
@@ -899,7 +899,7 @@ class Grid:
     def clean(self,
               stencil: int = 3,
               selection: IntSequence = None,
-              periodic: bool = True) -> "Grid":
+              periodic: bool = True) -> 'Grid':
         """
         Smooth grid by selecting most frequent material index within given stencil at each location.
 
@@ -939,7 +939,7 @@ class Grid:
                    )
 
 
-    def renumber(self) -> "Grid":
+    def renumber(self) -> 'Grid':
         """
         Renumber sorted material indices as 0,...,N-1.
 
@@ -958,7 +958,7 @@ class Grid:
                    )
 
 
-    def rotate(self, R: Rotation, fill: int = None) -> "Grid":
+    def rotate(self, R: Rotation, fill: int = None) -> 'Grid':
         """
         Rotate grid (pad if required).
 
@@ -998,7 +998,7 @@ class Grid:
     def canvas(self,
                cells: IntSequence = None,
                offset: IntSequence = None,
-               fill: int = None) -> "Grid":
+               fill: int = None) -> 'Grid':
         """
         Crop or enlarge/pad grid.
 
@@ -1049,7 +1049,7 @@ class Grid:
                    )
 
 
-    def substitute(self, from_material: IntSequence, to_material: IntSequence) -> "Grid":
+    def substitute(self, from_material: IntSequence, to_material: IntSequence) -> 'Grid':
         """
         Substitute material indices.
 
@@ -1077,7 +1077,7 @@ class Grid:
                    )
 
 
-    def sort(self) -> "Grid":
+    def sort(self) -> 'Grid':
         """
         Sort material indices such that min(material) is located at (0,0,0).
 
@@ -1103,7 +1103,7 @@ class Grid:
                         vicinity: int = 1,
                         offset: int = None,
                         trigger: IntSequence = [],
-                        periodic: bool = True) -> "Grid":
+                        periodic: bool = True) -> 'Grid':
         """
         Offset material index of points in the vicinity of xxx.
 
diff --git a/python/damask/_vtk.py b/python/damask/_vtk.py
index 787aa3c72..4e3f27e0e 100644
--- a/python/damask/_vtk.py
+++ b/python/damask/_vtk.py
@@ -2,7 +2,7 @@ import os
 import warnings
 import multiprocessing as mp
 from pathlib import Path
-from typing import Union, Optional, Literal, List
+from typing import Union, Literal, List
 
 import numpy as np
 import vtk
@@ -10,7 +10,7 @@ from vtk.util.numpy_support import numpy_to_vtk            as np_to_vtk
 from vtk.util.numpy_support import numpy_to_vtkIdTypeArray as np_to_vtkIdTypeArray
 from vtk.util.numpy_support import vtk_to_numpy            as vtk_to_np
 
-from ._typehints import FloatSequence
+from ._typehints import FloatSequence, IntSequence
 from . import util
 from . import Table
 
@@ -38,8 +38,7 @@ class VTK:
 
 
     @staticmethod
-    #ITERABLES PROPER
-    def from_image_data(cells: np.ndarray, size: np.ndarray, origin: Optional[np.ndarray] = np.zeros(3)) -> "VTK":
+    def from_image_data(cells: IntSequence, size: FloatSequence, origin: FloatSequence = np.zeros(3)) -> 'VTK':
         """
         Create VTK of type vtk.vtkImageData.
 
@@ -63,13 +62,13 @@ class VTK:
         vtk_data = vtk.vtkImageData()
         vtk_data.SetDimensions(*(np.array(cells)+1))
         vtk_data.SetOrigin(*(np.array(origin)))
-        vtk_data.SetSpacing(*(size/cells))
+        vtk_data.SetSpacing(*(np.array(size)/np.array(cells)))
 
         return VTK(vtk_data)
 
 
     @staticmethod
-    def from_rectilinear_grid(grid: np.ndarray, size: FloatSequence, origin: FloatSequence = np.zeros(3)) -> "VTK":
+    def from_rectilinear_grid(grid: np.ndarray, size: FloatSequence, origin: FloatSequence = np.zeros(3)) -> 'VTK':
         """
         Create VTK of type vtk.vtkRectilinearGrid.
 
@@ -101,7 +100,7 @@ class VTK:
 
 
     @staticmethod
-    def from_unstructured_grid(nodes: np.ndarray, connectivity: np.ndarray, cell_type: str) -> "VTK":
+    def from_unstructured_grid(nodes: np.ndarray, connectivity: np.ndarray, cell_type: str) -> 'VTK':
         """
         Create VTK of type vtk.vtkUnstructuredGrid.
 
@@ -141,7 +140,7 @@ class VTK:
 
 
     @staticmethod
-    def from_poly_data(points: np.ndarray) -> "VTK":
+    def from_poly_data(points: np.ndarray) -> 'VTK':
         """
         Create VTK of type vtk.polyData.
 
@@ -176,15 +175,16 @@ class VTK:
 
     @staticmethod
     def load(fname: Union[str, Path],
-             dataset_type: Literal['vtkImageData', 'vtkRectilinearGrid', 'vtkUnstructuredGrid', 'vtkPolyData'] = None) -> "VTK":
+             dataset_type: Literal['ImageData', 'UnstructuredGrid', 'PolyData'] = None) -> 'VTK':
         """
         Load from VTK file.
 
         Parameters
         ----------
         fname : str or pathlib.Path
-            Filename for reading. Valid extensions are .vti, .vtr, .vtu, .vtp, and .vtk.
-        dataset_type : {'vtkImageData', ''vtkRectilinearGrid', 'vtkUnstructuredGrid', 'vtkPolyData'}, optional
+            Filename for reading.
+            Valid extensions are .vti, .vtr, .vtu, .vtp, and .vtk.
+        dataset_type : {'ImageData', 'UnstructuredGrid', 'PolyData'}, optional
             Name of the vtk.vtkDataSet subclass when opening a .vtk file.
 
         Returns
@@ -193,7 +193,7 @@ class VTK:
             VTK-based geometry from file.
 
         """
-        if not os.path.isfile(fname):                                                  # vtk has a strange error handling
+        if not os.path.isfile(fname):                                                               # vtk has a strange error handling
             raise FileNotFoundError(f'No such file: {fname}')
         ext = Path(fname).suffix
         if ext == '.vtk' or dataset_type is not None:
@@ -423,7 +423,7 @@ class VTK:
         return writer.GetOutputString()
 
 
-    def show(self) -> None:
+    def show(self):
         """
         Render.
 
diff --git a/python/damask/util.py b/python/damask/util.py
index d7f674a1c..2872762b9 100644
--- a/python/damask/util.py
+++ b/python/damask/util.py
@@ -9,14 +9,14 @@ import re
 import fractions
 import collections.abc as abc
 from functools import reduce
-from typing import Union, Tuple, Iterable, Sequence, Callable, Dict, List, Any, Literal, Optional
+from typing import Union, Tuple, Iterable, Callable, Dict, List, Any, Literal, Optional
 from pathlib import Path
 
 import numpy as np
 import h5py
 
 from . import version
-from ._typehints import FloatSequence, IntSequence
+from ._typehints import FloatSequence
 
 # limit visibility
 __all__=[