Please note: This article is meant to be a resource to printmakers and other interested people. Permission to reproduce this article is hereby granted as long as my name, Stephen McMillan, stays on it in all forms of reproduction.
The, "Aquatint Class", section has a step-by-step example for the print, "Petaluma Oaks"..


For many printmakers, getting a good aquatint has been an elusive and frustrating quest.

This article relates some of my experience with aquatint and is meant to help you get the results

you want with aquatint. It is written for the experienced etcher. It assumes knowledge of basic

etching procedures including plate preparation, studio safety, and intaglio printing.

Aquatints can produce a vast range of tonal values and textural effects in an etching. With

the knowledge of a few simple determining factors an artist can choose precisely what kind of

aquatint to use for the etching. The most important factors in creating an aquatint are: the amount

and grain size of rosin on the plate, the degree of melting of the rosin onto the plate, and the

amount of time the plate is acid-etched.

Probably the most common mistake made in attempting to do an aquatint is to put too

little rosin on the plate. To counter this it can be useful to put more rosin onto the plate than you

think is needed. It was through intentionally "over-rosining" that I found out about very dense,

and ultra dense aquatints, which I have used in a number of prints. Whether doing a hand

dropped, box dropped, or even spray can aquatint, it is vital that an adequate amount of the

surface of the plate be protected from the acid during the etch. Once too much of the surface has

been etched away it is very difficult to repair the damage short of scraping, burnishing and

starting over. It is therefore crucial that enough rosin get on the plate. My own rule of thumb is

to drop at least enough rosin onto the plate to obscure the metal when viewed from about 30

degrees up from the plate. For fine-grained rosin the coverage should appear even heavier since

the grains are smaller and will spread out less when melted onto the plate.

Another important consideration in dropping rosin onto the plate is the size of the

individual grains of rosin. Some rosins are pre-ground and will have nothing but fine grains.

These rosins are excellent for fine-grained aquatints but can be problematical for coarser ones.

Hand-ground lump rosin, whether used in an aquatint box or hand dropped, allows for a much

greater range of grain sizes. The variably sized grains of rosin will fall at different rates in a

box, thus giving you some control over what size of rosin will settle onto the plate. After the

rosin has been raised in the box, the larger, heavier rosin grains fall first, while the finer grains

float down much more slowly. To get coarser grains the plate is put onto the box soon after

the rosin is raised. If only larger rosin grains are wanted, the plate should be removed after

about a minute in the box. To get finer grains the plate should go into the box anywhere from

15 seconds to more than a minute after the rosin is raised, depending on how fine a rosin grain

is desired. Since much of the rosin will have dropped before the plate is in the box, the plate

may have to be put into the box a two or three times before there is enough rosin on it. In most

cases it is not necessary to try to isolate a narrow range of rosin grain sizes. I usually place a

plate in the box a few seconds after the dust is raised and then leave it in for at least 10 minutes.


Aquatint boxes vary quite a bit, so it is important to get a feel for the characteristics of the

particular box you are using. A good box should deposit enough rosin after one time in the

box, but unfortunately some require that two or more drops be done before heating the plate. If

a box does not deposit enough rosin it is also possible that the box needs more rosin to be

ground and added to it. Some boxes require more vigorous cranking than others and so may

just need more strength from you. If you are working with an unfamiliar box it is advisable to

do a few test aquatints to get a sense of how that one works. I have learned a lot through doing

test plates. In a relatively short period of time you can try many rosining and heating variations,

while developing a feel for the process.


Once the rosin is on the plate, heat is applied to melt it onto the plate. The amount of heat

and rate of application determine how the rosin will melt. Enough heat must be applied to at

least melt the grains until they are hemispheres stuck onto the plate. Under-heated rosin will

not adhere to the plate well and will therefore not protect enough of the plate. When lump rosin

melts the first thing to look for is the change from dry amber-colored dust into wet transparent

dots. It is easiest to see this transition happening by viewing the plate from a very low angle.

A small magnifying lens is a useful tool in seeing how the melting is progressing, particularly

with a fine-grained aquatint. It takes a bit of practice to find the best angle and lighting to see

the rosin on the plate. I use the hand lens on a Swiss Army knife. A geologist's 10X hand lens

or a jeweler's loupe also works well. For the fine-grained aquatints the plate should be heated

gradually, with only enough to just melt the grains onto the plate.

There are a few ways to heat a plate. The most common is a hot plate. Set the hot plate

at about 200 to 250 to melt fine grain lump rosin onto a plate. Different rosins melt at different

temperatures, so you may need to experiment. Place the rosined plate onto a sheet, or several

sheets, of paper on the hot plate. I use about four layers of heavy paper bag type paper. This

will help avoid hot spots and will make it easier to move the plate when needed. The rosin may

not melt evenly, so be ready to move and gently tip the plate to get the heat were you want it.

Uneven heating can be a real problem with larger plates, especially if they are larger than the

hot plate. If available, a gas flame wand works well for larger plates. There must also be a

raised screen of some sort to set the plate on while the flame is moved under it. Another

alternative to a gas flame is an alcohol soaked cotton ball in a frying pan. Be sure to have a

tight fitting lid to extinguish the flame! When using a gas flame wand or alcohol to heat the

plate, particular care must be taken to gradually heat the plate if a fine grained aquatint is

desired. This method can melt rosin so fast that the small grains melt together. As more heat is

applied, the grains spread, becoming larger and covering more of the metal. The resulting

aquatint is grainier and denser. If you start with larger grains on the plate they will tend to

spread out more than the fine grains. In either case, the addition of heat will cause the rosin to

continue to spread, coalesce, and cover more metal. It is possible to overheat the rosin and

totally cover the plate. The smoother the surface of a plate, the less likely it is that an aquatint

will totally cover it. Conversely, on a rougher plate, such as a previously etched aquatint, it is

much easier to over melt the rosin. A rougher surface tends to draw the liquid rosin out while a

polished surface will hold it at bay. It is surprising how much rosin and heat can be applied to

a plate without totally over-melting it. To produce a very dense highly textual aquatint I use a

gas flame wand to really fry a heavily rosined polished plate until it looks very wet and shiny,

and gives off smoke. I might not have found out how to do this if I had not tried to over-rosin

and overheat test plates. One caught fire and yet still produced an interesting aquatint!


After the rosin is in place the plate is ready to be acid etched. Copper is generally

etched in Dutch Mordant. The mixture I use is 25 parts water, five parts hydrochloric acid, one

part potassium chlorate crystals, and at least several parts old Dutch Mordant. If old acid is not

available a scrap of copper can be put into the acid for an hour or so. A common acid mixture

for zinc is 12 parts water to one part nitric acid. 12 to one nitric etches zinc about three to four

times faster than Dutch Mordant etches copper. The etch times needed to create a full tonal range

over an aquatint depends on the grain size of the aquatint, and the percent of metal exposed.

A very fine-grained aquatint could over-etch after only 10 minutes in Dutch Mordant while a

very dense aquatint could be etched 10 hours. The smaller the grain of an aquatint, the faster

the acid will etch under the rosin. Even though Dutch Mordant tends to etch down it still will

undercut the rosin given enough time. As the grain size increases so does the maximum etch

time possible. The percent of metal covered also makes a large difference. Light coverage will

over-etch quickly while heavy coverage can be etched much longer. A very dense aquatint can

be etched for several hours in Dutch mordant, and yet still leave enough original surface

remaining for another aquatint to be dropped onto. At the lighter end of the scale, a very

fine-grained, medium dense aquatint may need to be etched only 10 seconds to produce a light

tone while a coarse grain, very dense aquatint may need 10 minutes for a light tone. Given the

large variation of etch time in relation to tone produced it is advisable to make test plates to help

in determining what etch time produces what tone over a particular grain and density of aquatint.


The temperature of the acid will effect the etch speed, so that should be taken into

account if the temperature in the studio changes much. Longer times may be needed when

using colder acid, and shorter times for that hot summer day. I have not done any quantitative

tests with acid temperature, but would guess that etch times change by a factor of about two

every 10 to 15 degrees Celsius. This is only a guess. In Summer my acid is about 21 degrees,

and in winter it gets down to about 14 degrees. In Winter I generally etch about one half time


Between etches the plate should be examined with a hand lens. The lens is particularly

useful in determining how close the aquatint is to being etched to the maximum depth, short of

over etching, and ruining the plate. It is very important to maintain visual contact with the

aquatint, both when putting it onto the plate and when etching it into the plate. Much of your

success with aquatint depends on knowing what looks right. As you develop your skills with

aquatint you will learn what to look for, both with the lens and with unaided eyes.


Generally an aquatint is used to create a number of tones on the plate. A stop out

material is used to paint out areas of the plate between etches, usually starting with a paint-out

before any etching is done and progressing tone by tone to a dark, deeply etched tone. I have

always used asphaltum thinned some with kerosene or mineral spirits as the stop-out, though

there are a number of other stop-out materials available.

Another way to achieve a tonal range is to etch an entire plate to a black tone and then

use a burnisher to draw in the lighter tones. One advantage of this is that the pre-etched plate

can be worked on far from the studio, even in the wilderness. A burnished aquatint can be

proofed at any time during the drawing process since the rosin and acid have already done their

job. Although the resultant print will look somewhat like a mezzotint it does have a distinct

quality of its own. Some prints done this way are: Easy Chair, Lake of the Woods, Leaf Rhythms,

and Reflections and Carp.

An additional way to get a tonal range is to do a creep etch, which is done by allowing

the acid to gradually move up the surface of the aquatinted plate. For short creep etches the

plate can be gradually lowered into the acid. For longer creep etches the acid tray is blocked up

to a gradual slope, the plate placed on the slope, and then acid is slowly poured into the tray.

A long creep over a very dense aquatint can last well over an hour. I go into more detail on this

in my article, "Creep Etch".

Sometimes several aquatints are needed to create the desired image on the plate. As long

as enough of the original surface remains after the previous etches, a plate can be re-aquatinted

and re-etched. Use a hand lens to inspect the areas to be re-etched. If less than 20 percent of the

original surface remains, an additional aquatint is very likely to over-etch quickly. Only 20

percent is already on the fragile side. With 40 percent or more the plate should hold up to

further etching.

The re-rosining should cover the plate well, though not always as heavily as the first.

The etched-in texture already on the plate causes the rosin to spread out faster when it is heated,

making it easier to over-melt the rosin on the plate. The etched-in texture also makes it more

difficult to see how well the new aquatint is melting, and if it is adequately covering the plate.

This will definitely test your hand lens skills. Another possible problem is that on a variably

etched plate the rosin may spread out at different rates over different textures. That is, it may

be sparse on un-etched areas, but rather dense over well etched areas. This is much more likely

to be a problem with a second aquatint over a fine grain aquatint because the finer texture will

make the rosin spread more that a coarser one will. Generally when doing multiple aquatints

the coarser grained aquatints are done first, and the finer ones last. This way the smaller grains

of the fine grain aquatint rest on top of the larger "mesas" left by the previously etched coarse

aquatint. Additional aquatints are usually etched much less than the first one, both because of

the smaller grain size, and because less of the original surface remains to be etched. An image

can be gradually built up, using a number of aquatints, and other etching techniques. The only

limit is your imagination and patience. Always remember to wear your industrial dust and acid

fume masks when you work with these noxious chemicals!

Stephen McMillan © 1993 (revised 2000)