diff --git a/Project.toml b/Project.toml
index e8bf8e5..110e927 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "TidierPlots"
 uuid = "337ecbd1-5042-4e2a-ae6f-ca776f97570a"
 authors = ["Randall Boyes <33524191+rdboyes@users.noreply.github.com> and contributors"]
-version = "0.6.2"
+version = "0.6.3"
 
 [deps]
 CairoMakie = "13f3f980-e62b-5c42-98c6-ff1f3baf88f0"
diff --git a/src/TidierPlots.jl b/src/TidierPlots.jl
index afd023b..fab30be 100644
--- a/src/TidierPlots.jl
+++ b/src/TidierPlots.jl
@@ -99,6 +99,11 @@ export scale_colour_continuous, scale_color_continuous
 export scale_colour_discrete, scale_color_discrete
 export scale_colour_manual, scale_color_manual
 
+# transforms
+
+export cat_inseq, cat_inorder, number_on_axis, as_is, discard, verbatim, kernel_density_2d
+export as_color
+
 const plot_log = Ref{Bool}(true)
 const plot_show = Ref{Bool}(true)
 const plot_pluto = Ref{Bool}(true)
diff --git a/src/aes.jl b/src/aes.jl
index 2ea9202..509f501 100644
--- a/src/aes.jl
+++ b/src/aes.jl
@@ -1,7 +1,32 @@
 function aes(args...; kwargs...)
+    col_transforms = Dict()
+    aes_args = Symbol[]
+    aes_kwargs = Dict{String, Symbol}()
+
+    for arg in args
+        if arg isa Pair
+            push!(col_transforms, arg)
+            push!(aes_args, arg[1])
+        else
+            push!(aes_args, Symbol(arg))
+        end
+    end
+
     d = Dict(kwargs)
-    return Aesthetics(Symbol.([args...]),
-        Dict([String(key) => Symbol(d[key]) for key in keys(d)]))
+
+    for (k, v) in d
+        if v isa Pair
+            push!(col_transforms, v)
+            push!(aes_kwargs, String(k) => Symbol(v[1]))
+        else
+            push!(aes_kwargs, String(k) => Symbol(v))
+        end
+    end
+        
+    return Aesthetics(
+            aes_args,
+            aes_kwargs,
+            col_transforms)
 end
 
 macro aes(exprs...)
@@ -22,7 +47,7 @@ macro aes(exprs...)
             push!(positional, Symbol(aes_ex))
         end
     end
-    return Aesthetics(positional, aes_dict)
+    return Aesthetics(positional, aes_dict, Dict())
 end
 
 @eval const $(Symbol("@es")) = $(Symbol("@aes"))
\ No newline at end of file
diff --git a/src/extract_aes.jl b/src/extract_aes.jl
index 1185da7..c217c23 100644
--- a/src/extract_aes.jl
+++ b/src/extract_aes.jl
@@ -2,6 +2,7 @@ function make_aes_extractor(required_aes)
     return function extract_aes(args, kwargs)
         aes_dict = Dict{String, Symbol}() 
         args_dict = Dict{String, Any}() 
+        transforms = nothing
 
         for arg in args
             if arg isa DataFrame
@@ -21,13 +22,23 @@ function make_aes_extractor(required_aes)
                     end
                 end  
                 aes_dict = merge(aes_dict, arg.named)
+                transforms = arg.column_transformations
             end
         end
 
+        if !isnothing(transforms)
+            rev_aes_dict = Dict([v => k for (k, v) in aes_dict])
+            transforms = Dict([Symbol(rev_aes_dict[k]) => [Symbol(rev_aes_dict[k])] => v for (k, v) in transforms])
+            println(transforms)
+        else
+            println("TRANSFORMS EMPTY")
+            transforms = Dict{Symbol, Pair{Vector{Symbol}, AesTransform}}()
+        end
+
         d = Dict(kwargs)
         args_dict = merge(args_dict, Dict([String(key) => d[key] for key in keys(d)]))
 
-        return (aes_dict, args_dict)
+        return (aes_dict, args_dict, transforms)
     end
 end    
 
diff --git a/src/geoms/geom_contour.jl b/src/geoms/geom_contour.jl
index af9fc4d..f4e7521 100644
--- a/src/geoms/geom_contour.jl
+++ b/src/geoms/geom_contour.jl
@@ -11,7 +11,7 @@ end
 geom_tile = geom_template("geom_tile", ["x", "y", "z"], :Heatmap)
 geom_contour = geom_template("geom_contour", ["x", "y"], :Contour; 
     aes_function = stat_density_2d,
-    column_transformations = Dict{Symbol, Pair{Vector{Symbol}, Function}}(
+    column_transformations = Dict{Symbol, Pair{Vector{Symbol}, AesTransform}}(
         :x => [:x]=>discard,
         :y => [:y]=>discard,
         :z => [:x, :y]=>kernel_density_2d))
diff --git a/src/geoms/geom_errorbar.jl b/src/geoms/geom_errorbar.jl
index 3eed125..2d43983 100644
--- a/src/geoms/geom_errorbar.jl
+++ b/src/geoms/geom_errorbar.jl
@@ -1,5 +1,5 @@
 function geom_errorbar(args...; kwargs...)
-    aes_dict, args_dict = extract_aes(args, kwargs)
+    aes_dict, args_dict, transforms = extract_aes(args, kwargs)
 
     args_dict["geom_name"] = "geom_errorbar"
     
@@ -7,12 +7,12 @@ function geom_errorbar(args...; kwargs...)
         ["x", "ymin", "ymax"], # required aesthetics
         :Rangebars, # function for visual layer
         do_nothing,
-        Dict{Symbol, Pair{Vector{Symbol}, Function}}();
+        transforms;
         special_aes = Dict("width" => "whiskerwidth")) 
 end
 
 function geom_errorbarh(args...; kwargs...)
-    aes_dict, args_dict = extract_aes(args, kwargs)
+    aes_dict, args_dict, transforms = extract_aes(args, kwargs)
 
     args_dict["geom_name"] = "geom_errorbarh"
     args_dict["errorbar_direction"] = :x
@@ -21,7 +21,7 @@ function geom_errorbarh(args...; kwargs...)
         ["y", "xmin", "xmax"], # required aesthetics
         :Rangebars, # function for visual layer
         do_nothing,
-        Dict{Symbol, Pair{Vector{Symbol}, Function}}();
+        transforms;
         special_aes = Dict("width" => "whiskerwidth")) 
 
 end
diff --git a/src/geoms/geom_hvline.jl b/src/geoms/geom_hvline.jl
index 739f084..ec680ea 100644
--- a/src/geoms/geom_hvline.jl
+++ b/src/geoms/geom_hvline.jl
@@ -1,5 +1,5 @@
 function geom_hline(args...; kwargs...)
-    aes_dict, args_dict = extract_aes(args, kwargs)
+    aes_dict, args_dict, transforms = extract_aes(args, kwargs)
     
     args_dict["geom_name"] = "geom_hline"
 
@@ -11,7 +11,8 @@ function geom_hline(args...; kwargs...)
     return build_geom(aes_dict, args_dict, 
         ["yintercept"], # required aesthetics
         :HLines,
-        do_nothing, Dict{Symbol, Pair{Vector{Symbol}, Function}}()) # function for visual layer  
+        do_nothing, 
+        transforms) # function for visual layer  
 end
 
 function geom_vline(args...; kwargs...)
@@ -27,7 +28,8 @@ function geom_vline(args...; kwargs...)
     return build_geom(aes_dict, args_dict, 
         ["xintercept"], # required aesthetics
         :VLines,
-        do_nothing, Dict{Symbol, Pair{Vector{Symbol}, Function}}()) # function for visual layer   
+        do_nothing, 
+        transforms) # function for visual layer   
 end
 
 function geom_hline(plot::GGPlot, args...; kwargs...)
diff --git a/src/geoms/geom_smooth.jl b/src/geoms/geom_smooth.jl
index fb5ffe5..f83b40c 100644
--- a/src/geoms/geom_smooth.jl
+++ b/src/geoms/geom_smooth.jl
@@ -31,7 +31,7 @@ function geom_smooth(plot::GGPlot, args...; kwargs...)
 end
 
 function geom_smooth(args...; kwargs...)
-    aes_dict, args_dict = extract_aes(args, kwargs)
+    aes_dict, args_dict, transforms = extract_aes(args, kwargs)
     args_dict["geom_name"] = "geom_smooth"
 
     if haskey(args_dict, "method")
@@ -41,13 +41,13 @@ function geom_smooth(args...; kwargs...)
                         ["x", "y"],
                         :Lines, 
                         stat_linear,
-                        Dict{Symbol, Pair{Vector{Symbol}, Function}}()),
+                        transforms),
                     build_geom(aes_dict,
                         args_dict, 
                         ["x", "lower", "upper"],
                         :Band, 
                         stat_linear,
-                        Dict{Symbol, Pair{Vector{Symbol}, Function}}())]
+                        transforms)]
         end
     end
 
@@ -56,7 +56,7 @@ function geom_smooth(args...; kwargs...)
                       ["x", "y"],
                       :Lines, 
                       stat_loess,
-                      Dict{Symbol, Pair{Vector{Symbol}, Function}}())
+                      transforms)
 end
 
 function stat_loess(aes_dict::Dict{String, Symbol}, 
diff --git a/src/geoms/geom_template.jl b/src/geoms/geom_template.jl
index a520b77..de339a1 100644
--- a/src/geoms/geom_template.jl
+++ b/src/geoms/geom_template.jl
@@ -2,13 +2,13 @@ function geom_template(name::AbstractString,
                        required_aes::AbstractArray, 
                        spec_api_function::Symbol;
                        aes_function::Function = do_nothing,
-                       column_transformations::Dict{Symbol, Pair{Vector{Symbol}, Function}} = Dict{Symbol, Pair{Vector{Symbol}, Function}}(), 
+                       column_transformations::Dict{Symbol, Pair{Vector{Symbol}, AesTransform}} = Dict{Symbol, Pair{Vector{Symbol}, AesTransform}}(), 
                        extra_args::Dict = Dict())
 
     extract_geom_aes = make_aes_extractor(required_aes)
 
     function geom_function(args...; kwargs...)
-        aes_dict, args_dict = extract_geom_aes(args, kwargs)
+        aes_dict, args_dict, transforms = extract_geom_aes(args, kwargs)
         args_dict["geom_name"] = name
         args_dict = merge(args_dict, extra_args)
 
@@ -16,7 +16,7 @@ function geom_template(name::AbstractString,
             required_aes,
             spec_api_function,
             aes_function, 
-            column_transformations)
+            merge(transforms, column_transformations))
     end
 
     function geom_function(plot::GGPlot, args...; kwargs...)
diff --git a/src/geoms/geom_text.jl b/src/geoms/geom_text.jl
index a1be110..0b963a3 100644
--- a/src/geoms/geom_text.jl
+++ b/src/geoms/geom_text.jl
@@ -1,4 +1,4 @@
 geom_text = geom_template("geom_text", ["x", "y"], :Text; 
-    column_transformations = Dict{Symbol, Pair{Vector{Symbol}, Function}}(:text => [:text]=>verbatim))
+    column_transformations = Dict{Symbol, Pair{Vector{Symbol}, AesTransform}}(:text => [:text]=>verbatim))
 geom_label = geom_template("geom_label", ["x", "y"], :Text; 
-    column_transformations = Dict{Symbol, Pair{Vector{Symbol}, Function}}(:text => [:text]=>verbatim))
\ No newline at end of file
+    column_transformations = Dict{Symbol, Pair{Vector{Symbol}, AesTransform}}(:text => [:text]=>verbatim))
\ No newline at end of file
diff --git a/src/structs.jl b/src/structs.jl
index 3823f71..d4c4bab 100644
--- a/src/structs.jl
+++ b/src/structs.jl
@@ -21,6 +21,7 @@ end
 struct Aesthetics
     positional::AbstractArray
     named::Dict
+    column_transformations::Dict
 end
 
 struct AxisOptions
diff --git a/src/transforms.jl b/src/transforms.jl
index b2cfc4e..3d171f3 100644
--- a/src/transforms.jl
+++ b/src/transforms.jl
@@ -14,13 +14,30 @@ struct PlottableData
     label_function::Any
 end
 
+# AesTransform acts like a class of functions
+
+struct AesTransform
+    fn::Function
+end
+
+# When called with the standard signature, an AesFunction object
+# calls its internal function with those arguments
+
+(at::AesTransform)(target::Symbol, source::Vector{Symbol}, data::DataFrame) = at.fn(target, source, data)
+
+# When called with a string or symbol, as would happen in an aes() call
+# returns a dict of the same type used in column_transformations
+
+(at::AesTransform)(sym::Symbol) = sym         => at
+(at::AesTransform)(str::String) = Symbol(str) => at
+
 # simplest one is as_is, which just gets a column 
 # exactly as it is in the DataFrame
 
-function as_is(target::Symbol, source::Vector{Symbol}, data::DataFrame)
+function as_is_fn(target::Symbol, source::Vector{Symbol}, data::DataFrame)
     return Dict{Symbol, PlottableData}(
         target => PlottableData(
-            data[!, source[1]],           # get the column out of the dataframe
+            data[!, source[1]],        # get the column out of the dataframe
             identity,                  # do nothing to it
             nothing,            
             nothing                   
@@ -28,6 +45,8 @@ function as_is(target::Symbol, source::Vector{Symbol}, data::DataFrame)
     )
 end
 
+as_is = AesTransform(as_is_fn)
+
 # verbatim has a similar goal, but for String columns
 
 function convert_to(type::Type)
@@ -43,9 +62,9 @@ function convert_to(type::Type)
     end
 end
 
-verbatim = convert_to(String)
+verbatim = AesTransform(convert_to(String))
 
-function number_on_axis(target::Symbol, source::Vector{Symbol}, data::DataFrame)
+function number_on_axis_fn(target::Symbol, source::Vector{Symbol}, data::DataFrame)
     return Dict{Symbol, PlottableData}(
         target => PlottableData(
             data[!, source[1]],                 # get the column out of the dataframe
@@ -56,11 +75,11 @@ function number_on_axis(target::Symbol, source::Vector{Symbol}, data::DataFrame)
     )
 end
 
-
+number_on_axis = AesTransform(number_on_axis_fn)
 
 # categorical array handling options for String columns
 
-function cat_inorder(target::Symbol, source::Vector{Symbol}, data::DataFrame)
+function cat_inorder_fn(target::Symbol, source::Vector{Symbol}, data::DataFrame)
     cat_column = data[!, source[1]]
     cat_array = CategoricalArray(cat_column,
         levels = unique(cat_column),
@@ -80,7 +99,9 @@ function cat_inorder(target::Symbol, source::Vector{Symbol}, data::DataFrame)
     )    
 end
 
-function cat_inseq(target::Symbol, source::Vector{Symbol}, data::DataFrame)
+cat_inorder = AesTransform(cat_inorder_fn)
+
+function cat_inseq_fn(target::Symbol, source::Vector{Symbol}, data::DataFrame)
     cat_array = CategoricalArray(data[!, source[1]])
 
     label_target = target == :x ? :xticks :
@@ -97,9 +118,11 @@ function cat_inseq(target::Symbol, source::Vector{Symbol}, data::DataFrame)
     )      
 end
 
+cat_inseq = AesTransform(cat_inseq_fn)
+
 # kernel density estimation for geom_contour
 
-function kernel_density_2d(target::Symbol, source::Vector{Symbol}, data::DataFrame)
+function kernel_density_2d_fn(target::Symbol, source::Vector{Symbol}, data::DataFrame)
 
     k = kde((data[!, source[1]], data[!, source[2]]))
 
@@ -115,12 +138,16 @@ function kernel_density_2d(target::Symbol, source::Vector{Symbol}, data::DataFra
     return return_dict
 end
 
+kernel_density_2d = AesTransform(kernel_density_2d_fn)
+
 # returns nothing, removing aes from graph
 
-function discard(target::Symbol, source::Vector{Symbol}, data::DataFrame)
+function discard_fn(target::Symbol, source::Vector{Symbol}, data::DataFrame)
     return Dict{Symbol, PlottableData}()
 end
 
+discard = AesTransform(discard_fn)
+
 # tweaks
 # takes an existing PlottableData object and modifies the makie_function