diff --git a/xs/src/libslic3r/Flow.cpp b/xs/src/libslic3r/Flow.cpp
index 42caf9f1a..cc87ec0bb 100644
--- a/xs/src/libslic3r/Flow.cpp
+++ b/xs/src/libslic3r/Flow.cpp
@@ -120,11 +120,11 @@ Flow::_width_from_spacing(float spacing, float nozzle_diameter, float height, bo
     return spacing + OVERLAP_FACTOR * height * (1 - PI/4.0);
 }
 
-// Calculate a new spacing to fill width with possibly integer number of lines,
-// the first and last line being centered at the interval ends.
-// This function possibly increases the spacing, never decreases, 
-// and for a narrow width the increase in spacing may become severe,
-// therefore the adjustment is limited to 20% increase.
+/// Calculate a new spacing to fill width with possibly integer number of lines,
+/// the first and last line being centered at the interval ends.
+/// This function possibly increases the spacing, never decreases, 
+/// and for a narrow width the increase in spacing may become severe,
+/// therefore the adjustment is limited to 20% increase.
 template <class T>
 T
 Flow::solid_spacing(const T total_width, const T spacing)
diff --git a/xs/src/libslic3r/Flow.hpp b/xs/src/libslic3r/Flow.hpp
index 7149df6b4..8be103a86 100644
--- a/xs/src/libslic3r/Flow.hpp
+++ b/xs/src/libslic3r/Flow.hpp
@@ -10,7 +10,8 @@ namespace Slic3r {
 constexpr auto BRIDGE_EXTRA_SPACING = 0.05;
 constexpr auto OVERLAP_FACTOR = 1.0;
 
-enum FlowRole {
+/// Enumeration for different flow roles
+enum FlowRole 
     frExternalPerimeter,
     frPerimeter,
     frInfill,
@@ -20,6 +21,8 @@ enum FlowRole {
     frSupportMaterialInterface,
 };
 
+
+/// Represents material flow; provides methods to predict material spacing. 
 class Flow
 {
     public:
@@ -28,7 +31,13 @@ class Flow
     
     Flow(float _w, float _h, float _nd, bool _bridge = false)
         : width(_w), height(_h), nozzle_diameter(_nd), bridge(_bridge) {};
+
+    /// Return the centerline spacing between two adjacent extrusions that have the same properties (width, etc).
+    /// Models as a rectangle with semicircles at the ends.
     float spacing() const;
+
+    /// Return the centerline spacing between two Flow objects (current and some other flow).
+    /// \remark this->spacing(other) == other.spacing(this)
     float spacing(const Flow &other) const;
     void set_spacing(float spacing);
     void set_solid_spacing(const coord_t total_width) {
@@ -48,12 +57,18 @@ class Flow
         return scale_(this->spacing(other));
     };
     
+
+    /// Static method to build a Flow object from an extrusion width config setting and some other context properties
     static Flow new_from_config_width(FlowRole role, const ConfigOptionFloatOrPercent &width, float nozzle_diameter, float height, float bridge_flow_ratio);
+
+    /// Static method to build a Flow object from a specified centerline spacing (center-to-center).
     static Flow new_from_spacing(float spacing, float nozzle_diameter, float height, bool bridge);
     template <class T> static T solid_spacing(const T total_width, const T spacing);
     
     private:
     static float _bridge_width(float nozzle_diameter, float bridge_flow_ratio);
+    /// Calculate a relatively sane extrusion width, based on height and nozzle diameter.
+    /// Algorithm used does not play nice with layer heights < 0.1mm. 
     static float _auto_width(FlowRole role, float nozzle_diameter, float height);
     static float _width_from_spacing(float spacing, float nozzle_diameter, float height, bool bridge);
 };