diff --git a/python/rateslib/curves/curves.py b/python/rateslib/curves/curves.py
index 0b07c0f0..890556ff 100644
--- a/python/rateslib/curves/curves.py
+++ b/python/rateslib/curves/curves.py
@@ -13,6 +13,7 @@
 from collections.abc import Callable
 from datetime import datetime, timedelta
 from math import comb, floor
+from os import urandom
 from typing import TYPE_CHECKING, Any
 from uuid import uuid4
 
@@ -252,9 +253,8 @@ def __init__(  # type: ignore[no-untyped-def]
 
         self._set_ad_order(order=ad)
 
-    @property
-    def _cache_id(self) -> int:
-        return self._cache_id_store
+    def __hash__(self) -> int:
+        return self._state_id
 
     def __eq__(self, other: Any) -> bool:
         """Test two curves are identical"""
@@ -636,7 +636,7 @@ def clear_cache(self) -> None:
         Alternatively the curve caching as a feature can be set to *False* in ``defaults``.
         """
         self._cache: dict[datetime, DualTypes] = dict()
-        self._cache_id_store: int = hash(uuid4())
+        self._state_id: int = hash(urandom(8))  # 64-bit entropy
 
     def _cached_value(self, date: datetime, val: DualTypes) -> DualTypes:
         if defaults.curve_caching:
@@ -702,6 +702,7 @@ def csolve(self) -> None:
             self.spline = PPSplineDual2(4, t_posix, None)
 
         self.spline.csolve(tau_posix, y, left_n, right_n, False)  # type: ignore[attr-defined]
+        self.clear_cache()
 
     def shift(
         self,
@@ -2584,13 +2585,12 @@ def index_value(self, date: datetime, interpolation: str = "daily") -> DualTypes
     def _get_node_vector(self) -> Arr1dObj | Arr1dF64:
         raise NotImplementedError("Instances of CompositeCurve do not have solvable variables.")
 
-    @property
-    def _cache_id_associate(self) -> int:
-        return hash(sum(curve._cache_id for curve in self.curves))
+    def _composited_hashes(self) -> int:
+        return hash(sum(hash(curve) for curve in self.curves))
 
     def _clear_cache(self) -> None:
         """
-        Clear the cache of values on a *CompositeCurve* type.
+        Clear the cache of values on a *CompositeCurve* type, and update the state id.
 
         Returns
         -------
@@ -2599,14 +2599,14 @@ def _clear_cache(self) -> None:
         Notes
         -----
         This method is called automatically when any of the composited curves
-        are detected to have been mutated, via their ``_cache_id``, which therefore
+        are detected to have been mutated, via their ``_state_id``, which therefore
         invalidates the cache on a composite curve.
         """
         self._cache: dict[datetime, DualTypes] = dict()
-        self._cache_id_store = self._cache_id_associate
+        self._state_id = self._composited_hashes()
 
     def _validate_cache(self) -> None:
-        if self._cache_id != self._cache_id_associate:
+        if hash(self) != self._composited_hashes():
             # If any of the associated curves have been mutated then the cache is invalidated
             self._clear_cache()
 
@@ -2975,6 +2975,11 @@ def __init__(
     def id(self):
         return self._id  # overloads Curve getting id from CurveObj
 
+    def __hash__(self) -> int:
+        # ProxyCurve is directly associated with its FXForwards object
+        self.fx_forwards._validate_cache()
+        return hash(self.fx_forwards)
+
     def __getitem__(self, date: datetime) -> DualTypes:
         self.fx_forwards._validate_cache()  # manually handle cache check
 
@@ -2985,12 +2990,6 @@ def __getitem__(self, date: datetime) -> DualTypes:
         _3: DualTypes = self.fx_forwards.fx_curves[self.coll_pair][date]
         return _1 / _2 * _3
 
-    @property
-    def _cache_id(self) -> int:
-        # the state of the cache for a ProxyCurve is fully dependent on the state of the
-        # cache of its contained FXForwards object, which is what derives its calculations.
-        return self.fx_forwards._cache_id
-
     def to_json(self) -> str:  # pragma: no cover  # type: ignore
         """
         Not implemented for :class:`~rateslib.fx.ProxyCurve` s.
diff --git a/python/rateslib/fx/fx_forwards.py b/python/rateslib/fx/fx_forwards.py
index 0559ace2..455629f2 100644
--- a/python/rateslib/fx/fx_forwards.py
+++ b/python/rateslib/fx/fx_forwards.py
@@ -161,7 +161,7 @@ def update(self, fx_rates: list[dict[str, float]] | NoInput = NoInput(0)) -> Non
             for fxr_obj, fxr_up in zip(self_fx_rates, fx_rates, strict=True):
                 fxr_obj.update(fxr_up)
         self._calculate_immediate_rates(base=self.base, init=False)
-        self._cache_id = self._cache_id_associate
+        self._state_id = self._composited_hashes()
 
     def __init__(
         self,
@@ -173,19 +173,20 @@ def __init__(
         self._validate_fx_curves(fx_curves)
         self.fx_rates: FXRates | list[FXRates] = fx_rates
         self._calculate_immediate_rates(base, init=True)
-        self._cache_id = self._cache_id_associate
-        pass
-
-    @property
-    def _cache_id_associate(self) -> int:
-        self_fx_rates = self.fx_rates if isinstance(self.fx_rates, list) else [self.fx_rates]
-        return hash(
-            sum(curve._cache_id for curve in self.fx_curves.values())
-            + sum(fxr._state_id for fxr in self_fx_rates)
+        self._state_id = self._composited_hashes()
+
+    def __hash__(self) -> int:
+        return self._state_id
+
+    def _composited_hashes(self) -> int:
+        self_fx_rates = [self.fx_rates] if not isinstance(self.fx_rates, list) else self.fx_rates
+        total = sum(hash(curve) for curve in self.fx_curves.values()) + sum(
+            hash(fxr) for fxr in self_fx_rates
         )
+        return hash(total)
 
     def _validate_cache(self) -> None:
-        if self._cache_id != self._cache_id_associate:
+        if hash(self) != self._composited_hashes():
             self.update()
 
     def _validate_fx_curves(self, fx_curves: dict[str, Curve]) -> None:
@@ -1050,7 +1051,7 @@ def _set_ad_order(self, order: int) -> None:
         else:
             self.fx_rates._set_ad_order(order)
         self.fx_rates_immediate._set_ad_order(order)
-        self._cache_id = self._cache_id_associate  # update the cache id after changing values
+        self._state_id = self._composited_hashes()  # update the cache id after changing values
 
     @_validate_caches
     def to_json(self) -> str:
diff --git a/python/rateslib/fx_volatility.py b/python/rateslib/fx_volatility.py
index e18fdfdf..cd2eb373 100644
--- a/python/rateslib/fx_volatility.py
+++ b/python/rateslib/fx_volatility.py
@@ -2,6 +2,7 @@
 
 from datetime import datetime, timedelta
 from datetime import datetime as dt
+from os import urandom
 from uuid import uuid4
 
 import numpy as np
@@ -118,6 +119,28 @@ def __init__(
 
         self._set_ad_order(ad)  # includes csolve
 
+    def clear_cache(self) -> None:
+        """
+        Clear the cache of values on a *Smile* type.
+
+        Returns
+        -------
+        None
+
+        Notes
+        -----
+        This should be used if any modification has been made to the *Smile*.
+        Users are advised against making direct modification to *Curve* classes once
+        constructed to avoid the issue of un-cleared caches returning erroneous values.
+
+        Alternatively the curve caching as a feature can be set to *False* in ``defaults``.
+        """
+        self._cache: dict[float, DualTypes] = dict()
+        self._state_id: int = hash(urandom(8))  # 64-bit entropy
+
+    def __hash__(self) -> int:
+        return self._state_id
+
     def __iter__(self):
         raise TypeError("`FXDeltaVolSmile` is not iterable.")
 
@@ -436,9 +459,7 @@ def csolve(self) -> None:
 
         self.spline = Spline(4, self.t, None)
         self.spline.csolve(tau, y, left_n, right_n, False)
-
-        # self._create_approx_spline_conversions(Spline)
-        return None
+        self.clear_cache()
 
     # def _build_datatable(self):
     #     """
@@ -524,7 +545,7 @@ def csolve(self) -> None:
     #     self.spline_u_delta_approx.csolve(u, delta.tolist()[::-1], 0, 0, False)
     #     return None
 
-    def _set_ad_order(self, order: int):
+    def _set_ad_order(self, order: int) -> None:
         if order == getattr(self, "ad", None):
             return None
         elif order not in [0, 1, 2]:
@@ -535,8 +556,7 @@ def _set_ad_order(self, order: int):
             k: set_order_convert(v, order, [f"{self.id}{i}"])
             for i, (k, v) in enumerate(self.nodes.items())
         }
-        self.csolve()
-        return None
+        self.csolve()  # also clears cache
 
     def plot(
         self,
@@ -625,6 +645,7 @@ def _set_node_vector(self, vector, ad):
                 *DualArgs[1:],
             )
         self.csolve()
+        self.clear_cache()
 
     def _get_node_vector(self):
         """Get a 1d array of variables associated with nodes of this object updated by Solver"""
diff --git a/python/tests/test_curves.py b/python/tests/test_curves.py
index d137b396..1837f720 100644
--- a/python/tests/test_curves.py
+++ b/python/tests/test_curves.py
@@ -1244,11 +1244,30 @@ def test_cache_id_update(self, method, args):
             },
             id="sofr",
         )
-        original = curve._cache_id
+        original = hash(curve)
         getattr(curve, method)(*args)
-        new = curve._cache_id
+        new = hash(curve)
         assert new != original
 
+    def test_csolve_clear_cache(self):
+        c = Curve(
+            nodes={dt(2000, 1, 1): 1.0, dt(2002, 1, 1): 0.99},
+            t=[
+                dt(2000, 1, 1),
+                dt(2000, 1, 1),
+                dt(2000, 1, 1),
+                dt(2000, 1, 1),
+                dt(2002, 1, 1),
+                dt(2002, 1, 1),
+                dt(2002, 1, 1),
+                dt(2002, 1, 1),
+            ],
+        )
+        before = hash(c)
+        c.csolve()
+        after = hash(c)
+        assert before != after
+
 
 class TestLineCurve:
     def test_repr(self):
@@ -1287,9 +1306,9 @@ def test_cache_id_update(self, method, args):
             },
             id="sofr",
         )
-        original = curve._cache_id
+        original = hash(curve)
         getattr(curve, method)(*args)
-        new = curve._cache_id
+        new = hash(curve)
         assert new != original
 
 
@@ -1354,7 +1373,7 @@ def test_typing_as_curve(self):
     @pytest.mark.parametrize(
         ("method", "args"), [("clear_cache", tuple()), ("_set_node_vector", ([0.99], 1))]
     )
-    def test_cache_id_update(self, method, args):
+    def test_state_id_update(self, method, args):
         curve = IndexCurve(
             nodes={
                 dt(2022, 1, 1): 1.0,
@@ -1363,9 +1382,9 @@ def test_cache_id_update(self, method, args):
             id="sofr",
             index_base=200.0,
         )
-        original = curve._cache_id
+        original = hash(curve)
         getattr(curve, method)(*args)
-        new = curve._cache_id
+        new = hash(curve)
         assert new != original
 
 
@@ -2062,10 +2081,10 @@ def test_cache_is_validated_on_getitem(self):
         curve = fxf.curve("cad", "eur")
         fxr1.update({"usdeur": 100000000.0})
         fxf.curve("eur", "eur")._set_node_vector([0.5], 1)
-        prior_id = fxf._cache_id
+        before = hash(fxf)
         curve[dt(2022, 1, 9)]
-        new_id = fxf._cache_id
-        assert prior_id != new_id
+        after = hash(fxf)
+        assert before != after
 
 
 class TestPlotCurve:
diff --git a/python/tests/test_fx.py b/python/tests/test_fx.py
index 418a8aaa..9ade24ec 100644
--- a/python/tests/test_fx.py
+++ b/python/tests/test_fx.py
@@ -1252,7 +1252,7 @@ class TestFXForwards:
             ("to_json", tuple()),
         ],
     )
-    def test_cache_id_update_on_fxr_update(self, method, args):
+    def test_hash_update_on_fxr_update(self, method, args):
         # test validate cache works correctly on various methods after FXRates update
         fxr1 = FXRates({"eurusd": 1.05}, settlement=dt(2022, 1, 3))
         fxr2 = FXRates({"usdcad": 1.1}, settlement=dt(2022, 1, 2))
@@ -1270,15 +1270,15 @@ def test_cache_id_update_on_fxr_update(self, method, args):
             },
         )
 
-        original_id = fxf._cache_id
+        before = hash(fxf)
         getattr(fxf, method)(*args)
         # no cache update is necessary
-        assert original_id == fxf._cache_id
+        assert before == hash(fxf)
 
         fxr1.update({"eurusd": 2.0})
         getattr(fxf, method)(*args)
         # cache update should have occurred
-        assert original_id != fxf._cache_id
+        assert before != hash(fxf)
 
     @pytest.mark.parametrize(
         ("method", "args"),
@@ -1291,7 +1291,7 @@ def test_cache_id_update_on_fxr_update(self, method, args):
             ("to_json", tuple()),
         ],
     )
-    def test_cache_id_update_on_curve_update(self, method, args):
+    def test_hash_update_on_curve_update(self, method, args):
         # test validate cache works correctly on various methods after Curve update
         fxr1 = FXRates({"eurusd": 1.05}, settlement=dt(2022, 1, 3))
         fxr2 = FXRates({"usdcad": 1.1}, settlement=dt(2022, 1, 2))
@@ -1309,12 +1309,12 @@ def test_cache_id_update_on_curve_update(self, method, args):
             },
         )
 
-        original_id = fxf._cache_id
+        before = hash(fxf)
         getattr(fxf, method)(*args)
         # no cache update is necessary
-        assert original_id == fxf._cache_id
+        assert before == hash(fxf)
 
         fxf.curve("eur", "eur")._set_node_vector([0.998], 1)
         getattr(fxf, method)(*args)
         # cache update should have occurred
-        assert original_id != fxf._cache_id
+        assert before != hash(fxf)
diff --git a/python/tests/test_fx_volatility.py b/python/tests/test_fx_volatility.py
index 429d2db3..53817912 100644
--- a/python/tests/test_fx_volatility.py
+++ b/python/tests/test_fx_volatility.py
@@ -341,6 +341,33 @@ def test_iter_raises(self) -> None:
         with pytest.raises(TypeError, match="`FXDeltaVolSmile` is not iterable."):
             fxvs.__iter__()
 
+    def test_hash(self):
+        fxvs = FXDeltaVolSmile(
+            nodes={0.25: 10.0, 0.5: 10.0, 0.75: 11.0},
+            delta_type="forward",
+            eval_date=dt(2023, 3, 16),
+            expiry=dt(2023, 6, 16),
+            id="vol",
+        )
+        assert hash(fxvs) == fxvs._state_id
+
+    @pytest.mark.parametrize(
+        ("method", "args"),
+        [("csolve", tuple()), ("_set_ad_order", (1,)), ("_set_node_vector", ([9.9, 9.8, 9.9], 1))],
+    )
+    def test_clear_cache(self, method, args):
+        fxvs = FXDeltaVolSmile(
+            nodes={0.25: 10.0, 0.5: 10.0, 0.75: 11.0},
+            delta_type="forward",
+            eval_date=dt(2023, 3, 16),
+            expiry=dt(2023, 6, 16),
+            id="vol",
+        )
+        before = hash(fxvs)
+        getattr(fxvs, method)(*args)
+        after = hash(fxvs)
+        assert before != after
+
 
 class TestFXDeltaVolSurface:
     def test_expiry_before_eval(self) -> None: