This step-by-step guide has been written by Tim Merrill to explain the process of glazing a 3D wooden carving created and machined using Aspire. Depending on the
project, not every 3D carving will benefit from glazing. However, as most projects end up on
the wall and the act of glazing allows the image to be recognized from across the room.
Looking at these two pictures, the one on the left is after machining and the one on the right after
glazing and finishing. It takes time and patience to achieve this result, but if you are going to invest
hours to carve a 3D image, why not spend a little longer and make it the best it can be.
Glazing has been used for hundreds of years, so the concept is not new. I learned about it years ago
and have used it in my furniture finishing. You can find information about glazing in just about any
quality finishing book, on numerous internet web sites and even videos on YouTube. After
completing my first few 3D carvings, I decided to experiment and see if glazing would give them
added depth. That was over 2 years ago and I have been doing it since. I am not a professional
furniture finisher, so if you are, or already have a finishing process for your carvings, then this
guide may not be for you.
The process I use can be separated into five major steps. This guide will take you through each step
and discuss techniques, tools and materials. For a 3D model, I have chosen the Wolf Head from Vector Art 3D. This model was chosen for three reasons: Its final appearance is greatly improved by
glazing (my opinion), the detail is enough to be a challenge, and it is one of the included 3D clip-art
models with Vectric's Aspire.
There are a couple of considerations when you choose wood for a 3D carving. For machining
quality, my favorite woods are walnut, cherry, and hard or soft maple. In my experience, you will
get better machining results and finer detail with the harder woods.
However, for glazing, you need a lighter wood so the darker glaze provides a contrast that produces
the feel of depth in the image. Therefore, I do almost all my projects in maple and the carvings for
this guide were done in hard maple. Should you do a carving in a darker wood, it is probably best
not to glaze it. There are light color glazes and stains, but I have never tried them in a situation
where the glaze is lighter than the base wood. This would be a good area should someone want to
do some experimenting. And if you do, please share your results, good or bad.
For me, oaks and ash fit into a special category. They machine great due to their hardness, but if
you are not careful, their strong grain patterns can become more dominant than the design. There is
so much personal preference in play here and I will stop at the above statement.
Glaze or Gel Stain?
The bottom line is both work and people use both. I looked in my finishing books and did internet
searches to see if there was a distinct difference between the two. I didn't find anything earth
shattering, simply that glazes are formulated for more open time and are easier to work. However, I
suspect there must be some trade secrets here or the marketing people would simply label every gel
stain as "gel stain and glaze." I have used gel stains as a glaze during furniture making because of
the larger variety of colors and shades available but have found two glazes I like for carvings, Burnt
Umber and Van Dyke Brown. For example, the Wolf Head carvings used in this guide were glazed
with Van Dyke Brown. You can also mix glazes from a single manufacturer to produce shade
variations or use different glazes in separate layers to obtain a special look. General Finishes also
markets a clear base that can be tinted with a water based dye or tint, but I have not tried that yet.
|This photo pretty well sums
up the finishing products I
normally use for doing 3D
carvings. General Finishes'
products are a favorite of
mine and I have used them for years for furniture
finishing. Similarly, I have
always been a fan of shellac
and Zinsser's Seal Coat
shellac is a relatively new
product on the market.
Although marketed as a
sanding sealer, it is quality
shellac which can be used as
both sanding sealer and
finish coat. Also, and most importantly, it is a dewaxed shellac. If you buy some to try, be sure it is
their Seal Coat product. They also market a Bullseye Shellac, but it is not dewaxed and you should
only use that if your entire finish will be shellac based.
If you have not used shellac before, it is a good idea to read about it first. However, a few important
points are in order here.
- Shellac comes in "pound cuts" (think in terms of viscosity or thickness, the higher the cut, the
thicker) which comes from the process of dissolving shellac flakes in alcohol. Seal Coat is premixed
as a 2 lb. cut when used directly from the can but can easily be changed by diluting it with
denatured alcohol. I normally start sealing with two to four coats of 1 lb. cut, then use a 2 lb. cut for
the remainder. You make a 1 lb. cut by mixing equal parts of denatured alcohol and Seal Coat
shellac, and you do not have to be exact. I buy the inexpensive wide mouth canning jars and mix the
shellac and denatured alcohol by eye. Write a description on the jar cover and you are good to go.
- Another tip for shellac use is to purchase some quality soft china bristle or badger hair brushes, use
them for shellac only, and do not clean your brushes when done. Just place them in a safe place,
where the bristles are not deformed and let them dry. Next time you go to use them, place the bristle
end in a jar of clean denatured alcohol and let it soften. It will only take 5-10 minutes to soften if the
brush has recently been used. If it has not been used for a while, it can take up to 30 minutes to
soften, so don't get concerned. My current brushes are over 6 years old, have never been cleaned,
but are like new when softened.
- The last point I will make about shellac is both a strength and weakness. Shellac is one of the few
finishes that will dissolve itself. That is why you do not want to spill alcohol on a shellac finished
piece of furniture. However, it also means that when used for multiple coats, you do not have to do
any sanding or preparation to the previous coat so the next will adhere. This is a big advantage with
a detailed carving. You should not have a big problem getting dust or other contaminates into a
fresh coat as it dries to the touch so fast. However, if you do get something in the finish, it is easy to
sand out before the next coat. Shellac dries very fast, and I can normally give a carving all the coats
it needs in an afternoon.
I have just started using General Finishes' new water-based Sanding Sealer. The 3D images
prepared and photographed for this guide had two coats of the sanding sealer applied before the
shellac and I am very impressed with it. Being water-based it did raise the grain, but that was
removed quite easily with synthetic steel wool. It also stiffened the "fuzzies" so they removed
easily. I have not tried applying the glaze right after the sanding sealer, but plan to do so soon. For
this guide, I decided to keep with a process that works: Multiple coats of shellac followed by the
We all want to go from machining to finishing without any preparation required and that is a good
goal for us all. However, we are working with wood, a fantastic material with no two pieces the
same. So let us accept the fact that we will most likely need to spend some hands-on time with our
projects before we start the finishing process. When I started with 3D, the images were simple and I
used abrasive methods such as sandpaper and sanding mops. However, as the images got more
detailed, using aggressive abrasives made it too easy to remove detail. Then, as I started using better
bits (covered in the next section) the machined surface quality improved to the point where the only
||material that had to be removed was "fuzzies" that occasionally appear in parts of the carving. Now
the focus, and tools used, is more to get into the detail areas and remove the fuzz that is left without
reducing detail. For the Wolf Head carvings, sandpaper was used only on the dish shape. Only a
brass wire brush and synthetic steel wool was used on the Wolf Head image. The picture shows my
tool collection, with the favorites being the brass wire brush, synthetic steel wool pads and Flexcut
Carving Scraper Set. The effectiveness of all these tools are increased significantly by first applying
one or two coats of either a sanding sealer or 1 lb. cut of dewaxed shellac.
Machining Tips and Bits
Without going into machine specific detail, there are two factors that can directly affect the quality
of your machining; the bit you use and the stepover you set for the finish pass.
Starting with the bit, the smaller diameter ball (round) nose bit you use, the more detail it will
produce. Therefore, for detail, a 1/16" diameter ball nose is better than a 1/8", which is better than a
1/4" and so on. These carvings of the Wolf Head are 7" in diameter and I choose to use a 1/16"
tapered ball nose bit to capture all the detail I could. Of course, the time to machine works against
you with the smaller diameter bit taking longer than a larger diameter bit. Not only is the machining
area at the tip of the bit smaller, but a smaller bit may require slower feed speeds to protect the bit
from breaking. If you own Aspire, the good news is a technique called rest machining. We will not
go into details here; you can find a tutorial on Vectric's web site and doing a forum search for rest
machining will get you even more info. With rest machining you can perform a quick finish path
using a large diameter ball nose bit, then go back with a smaller diameter bit and only machine the
detailed areas where the larger diameter bit couldn't get
For the finish path, I highly recommend the tapered ball
nose bits sold by Gary Beckwith. They are well designed,
quality made bits. While their initial price is
more than some, they will last a long time and save
countless hours in hand work. My 1/8" bit has more
hours on it than any other bit I have, and still cuts like
new. The bits are long, allowing for carving deeper
designs and the tapered tip adds strength. However, the
tapered design adds another consideration. If there are
vertical walls in your design; they will end up matching
the bit's taper instead of being vertical. However, I have
not found this to be an issue or present problems.
For the roughing pass, I normally use a 1/4" down
spiral router bit.
For the typical sized projects I do, this
bit is adequate and able to remove the majority of
material, leaving the minimum amount for the finish
pass. The down spiral leaves a good finish and does not
have the tendency to tear out or lift material.
The other important consideration is stepover. The smaller the stepover, the better the finish, but the
longer the machining time. Realize there is a point where a smaller stepover will still increase
machining time, but the increase in finish quality will be insignificant. I normally use 8% and get
great results. However, I have also used stepover values from 7% to 10% depending on the image I
was machining, the bit's diameter and the overall size of the carving.
Roughing Pass or Not?
This is another good question with no correct answer; it really depends on your personal preference.
My thoughts are simple: I do not want to trade a $50 bit for a few minutes of machine time. If you
look on the Vectric forum, you can find some threads where people give their techniques for using a
finish pass only and they do it successfully. However, I will give you one tip if you want to do that:
Do not use an offset finish path strategy, only use the raster. I have used the offset strategy and
observed the bit rise, travel to a different part of the design, plunge and start cutting. This was not a
problem for me as the roughing path had removed the bulk of the material. However, without a
roughing pass, this would have plunged the 1/8" bit about 3/4" and started cutting at 3 ips in walnut
and I am not sure it would have survived that.
Step 1: Machining and Preparation
If you have done everything right, you should now have a detailed carving almost ready for
finishing. For the less detailed areas, you can use sandpaper to touch up any rough areas just as you
would with any woodworking project. It is the detailed
areas that present a problem and the more detailed, the
greater the challenge. I have grown to like Flexcut's
Carving Scraper Set. It is not inexpensive, but high quality
and they do a great job if prepared correctly. If you have
never used a scraper, the technique is easy to learn. What is
more difficult is maintaining them so they continue to cut
effectively. This can be discouraging to the first time user.
For this carving, I first used some synthetic steel wool and
a scraper to remove the larger "fuzzies" followed by two
quick coats of sanding sealer applied about 30 minutes
apart. This stiffened the remaining fuzzies, allowing them
to be quickly removed with the synthetic steel wool. As I
said previously, my use of a water based sanding sealer is
relatively new. In the past, I would have applied two to four coats of 1 lb. cut shellac, which would have done the same thing to the fuzzies.
shellac and sanding sealer will help with preparing the surface, the difference being the shellac will
apply an amber tint, while the sanding sealer is clear or color neutral. After the sanding sealer (or
shellac) is completely dry, you can use scrapers, sandpaper and synthetic steel wool to create a
smooth surface for the glaze to "flow" over. Glaze is nice as it adds depth, but it will also highlight
any problem areas.
And finally, the carving must be clean before applying any finish products. Compressed air is the
best technique, but a powerful vacuum is a good alternative.
Step 2: Seal before Glazing
Glazing is not staining. With staining or dyeing, you
want the stain or dye to physically penetrate and change
the color of the wood. With glazing, you want the glaze
to "flow" over a smooth surface and tint the finish, not
penetrate the wood. Therefore, an important first step is
to seal the carving by some method before starting to
I always use Zinsser's Seal Coat shellac straight from
the can at a 2 lb. cut to seal the carvings. This picture
shows the carving after applying four coats of shellac.
This might sound like a big effort, but I was able to
apply four coats within ~3-4 hours and your carving
may not require this many coats. What you are trying to
achieve is when you look at the surface of the carving
in different light, it looks smooth and the shellac has
made it into all the detailed areas. But do exercise caution here; you can apply too much shellac and
After you are satisfied with the appearance, let it dry at least overnight before applying the water based
glaze in the next step.
Step 3: First Coat of Glaze
Once you are happy with the surface of your carving, it is
time to apply the first coat of glaze. My first coat of glaze
is normally very thin. This does two things, it starts the
glazing process and gives you a feel for how the carving is
going to look so you can better apply the second coat.
There is an important lesson here: It is always easy to apply
more coats, but once you have applied too much glaze,
especially in the deep and detailed parts of a carving,
removing it can be very difficult. Therefore, thin coats are
better than thick coats, and since the water based glazes dry
so fast, it does not take much time to perform this.
I have tried foam brushes, bristle brushes and folded rags to
apply the glaze but have finally settled on tapered round
brushes as the best method. The shape of the tapered round
brushes gives you a point to get into the detailed areas and
sides like a traditional paintbrush for the remaining areas. Mine were purchased from Lee Valley,
but are available from many sources.
To apply a coat of glaze using a brush, dip the brush into the glaze then use a piece of scrap wood or
cardboard to work the brush back and forth to remove excess glaze and even it out in the bristles.
You do not want to apply "globs" of glaze onto the model.
After applying the first coat of glaze, you can use three techniques to remove it from the high
points. The goal is to ensure the glaze remaining forms a smooth layer over the carving, with higher
areas being lighter.
My favorite technique is to work the surface with a dry round or flat paintbrush before the glaze has
dried (and you may have to work fast depending on drying conditions). Going in different
directions, you can work the glaze around and start to lighten up the higher areas while keeping
more glaze in the deeper areas. You do this by first holding the brush almost straight up and down
to use the tips of the bristles to work the deeper areas. Then, holding the brush at a shallow angle
(brush handle close to the surface), you can use the sides of the bristles to work the higher areas. As
an example, look at the neck fur of the Wolf to the left of the ear. If you use the brush in the
direction of the fur, which is almost horizontal, you can even out or remove glaze in the low points.
If you hold the brush at a shallow angle, and move it against the design or vertically in this case,
you will remove glaze from the high points and start to give definition to the design. You may need
to finish up with gentle, light strokes to ensure you do not leave streaks in the glaze that conflict
with the design.
Another technique to use before the glaze has dried is to make a pad out of a damp lint free rag
(such as cotton from an old tee shirt) or even a quality paper towel. Use this pad to work the higher
areas; you will not be able to get into the details with it. This technique works better for larger
designs. Again, go with the grain in case you do leave some streaks.
The final method is to wait until the glaze has dried to the touch then use a synthetic steel wool pad
to abrasively (but gently) remove glaze from the higher points. The longer the glaze has dried, the
harder it gets and this technique will take longer. Real steel wool works better, but do not use it if
you are using water-based products. You could end up with rust spots from the minute pieces of
metal that may stick into the finish and be hard to remove.
After satisfied with the first coat, let it dry completely and then proceed to the next step.
Step 4: Second Coat of Glaze
After the first coat has dried, inspect the results and
adjust as necessary. By using a fine synthetic steel wool
pad, you can lighten any areas that appear too dark. If
you do not do this, the second coat is only going to
make this area darker. At this time, you should be able
to start to see how you want the final image to look,
especially the parts you want to get peoples attention.
For the Wolf Head image, I wanted the eyes, ears and
nose to be the focal points. Therefore, before starting
the second coat, you should understand which areas can
be darkened, and which should be left lighter. Again,
remember that it is easy to darken areas more and
lighten the high points. It is not easy to lighten the
deeper areas if they are too dark.
Now you can apply and work a second coat using the same techniques used for the first coat.
Depending on the results you are trying to achieve, your second coat could be a light coat, a heavy
coat or variable depending on the area of the carving. I know this sounds difficult, but think it will
make sense as you do it. Do remember what I said about many thin coats better than one or two
heavy coats. Therefore, you may want to keep everything light in the
Step 5: Touch up and Final Finish
After you have applied the second coat and removed the excess from the high points, let it dry
overnight. After it is dry, you can still make minor adjustments. If an area is too dark, use one of the
methods to remove some more glaze from the high points. If an area is too light, or you remove too
much glaze, simply use a soft artist's brush and carefully apply more glaze to adjust. At this point,
you could carefully use sandpaper, sanding sponges and sanding mops to make final adjustments by
only removing glaze. You do not want to sand through to bare wood, and this takes care. One trick
it to use the finest grit abrasive you have. It may take longer to achieve the result you want, but this
is effectively giving you more control over the process.
When you are finally satisfied with your
results, the last step is to apply a final finish
to seal and protect the glaze. My two choices
are another one or two coats of Seal Coat
shellac or multiple coats of a spray lacquer.
Both work great and dry fast. One significant
difference between the two is the shellac will
continue to add an amber tint to the project
while the spray lacquer is clear. For spray
lacquer, I use Deft's Clear Wood finish in a
rattle can, which is widely available in my
area. Another decision you have to make is
how dull or glossy you want the final project
to be. Shellac will be glossy as shown in the
Step 5 picture. I prefer a satin finish, so if I
use shellac for the final coats, I will still give
it a few coats of Satin Deft Clear Wood
finish to reduce the gloss. If you only use a
spray lacquer for the final finish, you can
choose the level of gloss you want.
Trying to keep this guide simple, there are two good techniques that have not been covered. One is
staining or dyeing the wood before starting this glazing process. You can easily do this, but similar
to the discussion in the Wood Selection section, I would keep the color light to ensure the glaze still
provides the contrast between light and dark.
The second technique is the use of two different glaze tones to achieve different results. The two
glazes I typically use are Van Dyke Brown and Burnt Umber. Van Dyke Brown is a darker brown
with a hint of gray color and it is what I used for these carvings. Burnt Umber is lighter and browner
in color. I have used Van Dyke Brown for the first coat and followed that by Burnt Umber. The
effect is different from using just one or the other, and it would be a good area for you to do a little
experimenting if so inclined.
I hope that this has been presented in a manner you can understand and provides you with a good
starting point should you want to give it a go.
Thanks for reading,
Download the full PDF Guide >
Everything presented here is offered free for your personal use. If you do use any of the techniques,
products or tools mentioned, it is at your own risk. It is your responsibility to use your CNC and
other power tools safely, including wearing the proper personal safety gear. Also, please take the
time to read the MSDS sheets for all finishing products and observe the necessary safety
To make the process easier for you, specific products are mentioned by name and manufacturer
as appropriate. This is to provide you a starting point, assuming
if you use these products, you should be able to achieve the same results as shown. I am not saying
these are the only products to use or even the best products available, just the ones I like. I do not
have any financial connection with any of these companies and will not benefit financially if you
choose to use them.
You probably do not want to try this process for the first time using that unique piece of wood you
have been saving for that special project. Please start by doing some samples and practice, practice,