diff --git a/api/src/org/labkey/api/data/ColumnInfoTests.jsp b/api/src/org/labkey/api/data/ColumnInfoTests.jsp
index d7c901cd073..82ef6a79d29 100644
--- a/api/src/org/labkey/api/data/ColumnInfoTests.jsp
+++ b/api/src/org/labkey/api/data/ColumnInfoTests.jsp
@@ -25,6 +25,7 @@ This tests uses MockRequest to test some expected Headers and Meta tags for vari
         var result = col.convert(val);
         assertNotNull(result);
         //assertEquals(col.getJdbcType().getJavaClass(), result.getClass());
+        assertEquals(expected.getClass(), result.getClass());
         assertEquals(expected, result);
     }
 
@@ -159,9 +160,27 @@ This tests uses MockRequest to test some expected Headers and Meta tags for vari
                 case INTEGER -> {}
                 case REAL -> {}
                 case SMALLINT, TINYINT -> {}
-                case DATE -> {}
-                case TIME -> {}
-                case TIMESTAMP -> {}
+                case DATE ->
+                {
+                    testConvert(type, java.sql.Date.valueOf("2024-01-15"), "2024-01-15");
+                    testConvert(type, java.sql.Date.valueOf("2024-01-15"), java.sql.Date.valueOf("2024-01-15"));
+                    testConvertsToNull(type, null);
+                    testConvertsToNull(type, "");
+                }
+                case TIME ->
+                {
+                    testConvert(type, java.sql.Time.valueOf("14:30:00"), "14:30:00");
+                    testConvert(type, java.sql.Time.valueOf("14:30:00"), java.sql.Time.valueOf("14:30:00"));
+                    testConvertsToNull(type, null);
+                    testConvertsToNull(type, "");
+                }
+                case TIMESTAMP ->
+                {
+                    testConvert(type, java.sql.Timestamp.valueOf("2024-01-15 14:30:00"), "2024-01-15 14:30:00");
+                    testConvert(type, java.sql.Timestamp.valueOf("2024-01-15 14:30:00"), java.sql.Timestamp.valueOf("2024-01-15 14:30:00"));
+                    testConvertsToNull(type, null);
+                    testConvertsToNull(type, "");
+                }
                 case GUID -> {}
                 case ARRAY, NULL, OTHER -> { /* ignore */ }
                 default -> fail("We missed a JdbcType: " + type.name());
@@ -203,9 +222,27 @@ This tests uses MockRequest to test some expected Headers and Meta tags for vari
                 case BINARY -> {}
                 case FILE_LINK -> {}
                 case ATTACHMENT -> {}
-                case DATE_TIME -> {}
-                case DATE -> {}
-                case TIME -> {}
+                case DATE_TIME ->
+                {
+                    testConvert(type, java.sql.Timestamp.valueOf("2024-01-15 14:30:00"), "2024-01-15 14:30:00");
+                    testConvert(type, java.sql.Timestamp.valueOf("2024-01-15 14:30:00"), java.sql.Timestamp.valueOf("2024-01-15 14:30:00"));
+                    testConvertsToNull(type, null);
+                    testConvertsToNull(type, "");
+                }
+                case DATE ->
+                {
+                    testConvert(type, java.sql.Date.valueOf("2024-01-15"), "2024-01-15");
+                    testConvert(type, java.sql.Date.valueOf("2024-01-15"), java.sql.Date.valueOf("2024-01-15"));
+                    testConvertsToNull(type, null);
+                    testConvertsToNull(type, "");
+                }
+                case TIME ->
+                {
+                    testConvert(type, java.sql.Time.valueOf("14:30:00"), "14:30:00");
+                    testConvert(type, java.sql.Time.valueOf("14:30:00"), java.sql.Time.valueOf("14:30:00"));
+                    testConvertsToNull(type, null);
+                    testConvertsToNull(type, "");
+                }
                 case DOUBLE -> {}
                 case FLOAT -> {}
                 case DECIMAL -> {}
diff --git a/api/src/org/labkey/api/exp/PropertyType.java b/api/src/org/labkey/api/exp/PropertyType.java
index 6cf8a5dd32c..8d42cc373a2 100644
--- a/api/src/org/labkey/api/exp/PropertyType.java
+++ b/api/src/org/labkey/api/exp/PropertyType.java
@@ -593,8 +593,6 @@ protected Object convertExcelValue(Cell cell) throws ConversionException
                 {
                     throw new ConversionException(e);
                 }
-//                int offset = TimeZone.getDefault().getOffset(date.getTime());
-//                date.setTime(date.getTime() - offset);
             }
             return date;
         }
@@ -611,7 +609,7 @@ public Object convert(Object value) throws ConversionException
                 String strVal = value.toString();
                 if (DateUtil.isSignedDuration(strVal))
                     strVal = JdbcType.TIMESTAMP.convert(value).toString();
-                return ConvertUtils.convert(strVal, Date.class);
+                return ConvertUtils.convert(strVal, java.sql.Timestamp.class);
             }
         }
 
diff --git a/api/src/org/labkey/api/util/DateUtil.java b/api/src/org/labkey/api/util/DateUtil.java
index c919028cde2..1669e2bccca 100644
--- a/api/src/org/labkey/api/util/DateUtil.java
+++ b/api/src/org/labkey/api/util/DateUtil.java
@@ -1427,7 +1427,7 @@ public static Date combineDateTime(@Nullable Date date, @Nullable Date time)
             return date;
         if (null == date)
             return time;
-        Date newDate = (Date)date.clone();
+        Date newDate = new Date(date.getTime());
         newDate.setHours(time.getHours());
         newDate.setMinutes(time.getMinutes());
         newDate.setSeconds(time.getSeconds());
@@ -1444,7 +1444,7 @@ public static Date getDateOnly(@Nullable Date fullDate)
         int month = fullDate.getMonth();
         int date = fullDate.getDate();
 
-        return new Date(year, month, date);
+        return new java.sql.Date(year, month, date);
     }
 
     public static TimeZone getTimeZone()
diff --git a/api/src/org/labkey/api/util/SubstitutionFormat.java b/api/src/org/labkey/api/util/SubstitutionFormat.java
index 1dc46cf36f9..83eea5691b6 100644
--- a/api/src/org/labkey/api/util/SubstitutionFormat.java
+++ b/api/src/org/labkey/api/util/SubstitutionFormat.java
@@ -82,6 +82,8 @@ public Object format(Object value)
                 return defaultTimeFormat.format(value);
             else if (value instanceof java.sql.Date)
                 return date.format(value);
+            else if (value instanceof java.sql.Timestamp)
+                return defaultDateTimeFormat.format(value).replace('T', ' '); // replace T with whitespace for human readability
             else if (value instanceof Date dateVal)
             {
                 // both date and datetime column type are of type Date, format based on time portion of the date value