diff --git a/packages/scratch-core/src/container_models/base.py b/packages/scratch-core/src/container_models/base.py
index df2bb659..5d23c157 100644
--- a/packages/scratch-core/src/container_models/base.py
+++ b/packages/scratch-core/src/container_models/base.py
@@ -1,8 +1,8 @@
 from collections.abc import Sequence
 from functools import partial
 from typing import Annotated, TypeAlias
-
-from numpy import array, bool_, floating, number, uint8
+from functools import cached_property
+from numpy import array, bool_, floating, float64, number, uint8
 from numpy.typing import DTypeLike, NDArray
 from pydantic import (
     AfterValidator,
@@ -51,7 +51,7 @@ def validate_shape(n_dims: int, value: NDArray) -> NDArray:
 ]
 FloatArray: TypeAlias = Annotated[
     NDArray[floating],
-    BeforeValidator(partial(coerce_to_array, floating)),
+    BeforeValidator(partial(coerce_to_array, float64)),
     PlainSerializer(serialize_ndarray),
 ]
 BoolArray: TypeAlias = Annotated[
@@ -98,4 +98,22 @@ class ConfigBaseModel(BaseModel):
         extra="forbid",
         arbitrary_types_allowed=True,
         regex_engine="rust-regex",
+        revalidate_instances="always",
     )
+
+    def model_copy(self, *, update=None, deep=False):
+        copy = super().model_copy(update=update, deep=deep)
+        if update:
+            # Invalidate cached properties when any field changes
+            self._clear_cached_properties(copy)
+            # Validate model after updating
+            copy = self.model_validate(copy, by_alias=True, by_name=True)
+        return copy
+
+    @staticmethod
+    def _clear_cached_properties(instance: BaseModel):
+        """Dynamically find and clear all cached_property values from instance."""
+        for name in dir(type(instance)):
+            attr = getattr(type(instance), name, None)
+            if isinstance(attr, cached_property):
+                instance.__dict__.pop(name, None)
diff --git a/packages/scratch-core/src/container_models/scan_image.py b/packages/scratch-core/src/container_models/scan_image.py
index 5791f385..4b2b2fa1 100644
--- a/packages/scratch-core/src/container_models/scan_image.py
+++ b/packages/scratch-core/src/container_models/scan_image.py
@@ -41,14 +41,3 @@ def valid_data(self) -> FloatArray1D:
         valid_data = self.data[self.valid_mask]
         valid_data.setflags(write=False)
         return valid_data
-
-    def model_copy(self, *, update=None, deep=False):
-        copy = super().model_copy(update=update, deep=deep)
-        # Invalidate cached properties when any field changes
-        if update:
-            # Dynamically find and clear all cached_property attributes
-            for name in dir(type(copy)):
-                attr = getattr(type(copy), name, None)
-                if isinstance(attr, cached_property):
-                    copy.__dict__.pop(name, None)
-        return copy
diff --git a/packages/scratch-core/src/conversion/preprocess_impression/utils.py b/packages/scratch-core/src/conversion/preprocess_impression/utils.py
index 1330067b..85af69a7 100644
--- a/packages/scratch-core/src/conversion/preprocess_impression/utils.py
+++ b/packages/scratch-core/src/conversion/preprocess_impression/utils.py
@@ -29,7 +29,7 @@ def update_mark_scan_image(
     :param center: New center, or None to recompute from data.
     :return: New Mark instance with updated scan image.
     """
-    return mark.model_copy(update={"scan_image": scan_image, "_center": center})
+    return mark.model_copy(update={"scan_image": scan_image, "center_": center})
 
 
 Point2D = tuple[float, float]
diff --git a/packages/scratch-core/tests/container_models/test_validate_on_update.py b/packages/scratch-core/tests/container_models/test_validate_on_update.py
new file mode 100644
index 00000000..1faed57d
--- /dev/null
+++ b/packages/scratch-core/tests/container_models/test_validate_on_update.py
@@ -0,0 +1,57 @@
+import pytest
+from pydantic import ValidationError
+from container_models.base import ConfigBaseModel
+from container_models.scan_image import ScanImage
+import numpy as np
+
+
+class TestModel(ConfigBaseModel):
+    string_field: str
+    float_field: float
+
+
+@pytest.fixture(scope="module")
+def test_model() -> TestModel:
+    return TestModel(string_field="some_string", float_field=100.0)
+
+
+def test_model_copy_updates_correct_fields(test_model: TestModel):
+    updated = test_model.model_copy(update={"float_field": 150.0})
+    assert updated.float_field == 150.0
+
+
+def test_model_copy_raises_on_incorrect_fields(test_model: TestModel):
+    with pytest.raises(ValidationError):
+        test_model.model_copy(update={"float_field": "invalid_string"})
+
+
+def test_model_copy_raises_on_extra_field(test_model: TestModel):
+    with pytest.raises(ValidationError):
+        test_model.model_copy(update={"extra_field": "some_value"})
+
+
+def test_scan_image_model_copy_converts_updated_fields(
+    scan_image_with_nans: ScanImage,
+):
+    new_data = [[1, 2], [3, 4]]
+    updated = scan_image_with_nans.model_copy(update={"data": new_data})
+    assert np.array_equal(updated.data, new_data)
+
+
+def test_scan_image_model_copy_validates_updated_fields(
+    scan_image_with_nans: ScanImage,
+):
+    with pytest.raises(
+        ValidationError,
+        match="Array shape mismatch, expected 2 dimension\\(s\\), but got 1",
+    ):
+        scan_image_with_nans.model_copy(
+            update={"data": scan_image_with_nans.data.flatten()}
+        )
+    with pytest.raises(
+        ValidationError,
+        match="Array shape mismatch, expected 2 dimension\\(s\\), but got 0",
+    ):
+        scan_image_with_nans.model_copy(update={"data": "1"})
+    with pytest.raises(ValidationError, match="Input should be an instance of ndarray"):
+        scan_image_with_nans.model_copy(update={"data": {0: 1}})