Gilding course:  1 – Gesso

Gilding course: 1 – Gesso


This is video number 1 of the gilding course
made by Rinaldin. The complete course is made up of 11 videos
plus an introductory video. The first phase of gilding is applying the
gesso. The gesso is needed to close the wood’s pores
and prepare a smooth surface for the following processes. The frame looks like this after the gesso
has been applied. Some rabbit skin glue has to be mixed to the
gesso so that it sticks better. I’ll start by explaining how to prepare the
rabbit skin glue. The glue is in a granular form.
It has to be soaked in water for a night, until it becomes swells and has a gelatin
like appearance. The proportion is of 100 grams for every liter
of water. For this demonstration I put 20 grams of glue
in a container. I now add 200 grams of water while weighing
on the scales. I stir the water and the glue so that the
glue mixes in well and then I let it soak for a night. There’ll be a gelatin like mixture after a
night. We’ll have to heat it to about 50 degrees
to make it more liquid to mix it with the gesso. We therefore have to hold the container in
another pot with warm water. It’s best if the pot is of cast iron or terracotta
so that the temperature remains constant even if the heat is momentarily turned off. Now let’s move on to the gesso.
Firstly the gesso has to be sieved to ensure that it doesn’t contain any lumps or impurities. Also the rabbit skin glue has to be sieved.
For this process though the glue has to be liquid and has to be at about 50 degrees of
temperature. I now transfer the amount of glue I need in
another container. I add the gesso to the glue.
I place a spoonful of gesso at a time without forgetting to constantly stir as to avoid
small air bubbles from forming. There isn’t a precise amount of gesso to put.
I stop when I see that the gesso isn’t being incorporated from the glue anymore. Only at this point can the gesso and glue
be mixed together until the mix has the same consistency as it did before. At the end any left over glue can be stored
in the fridge or freezer to avoid it from spoiling. When it’ll be needed again it’ll have to be
heated once again in a pot with warm water (like before) to make it liquid. Rinaldin provides gesso in 1, 5, 25 Kg packages. It’s an “aired” gesso which means that it’s
a hydrated calcium sulfate which has been particularly ground and purified. It’s characteristics of impalpability and
softness to the touch make it completely suitable for gilding. The glue comes from rabbit skin waste and
is provided by Rinaldin in 1, 5, 25 Kg packages. I now proceed to the application of the gesso
to the frame. If you have brushes with metal rings you have
to pay attention that the gesso doesn’t get in contact with the ring as it’ll otherwise
oxidize. The oxidization would create some bubbles
on the gesso which would be visible after having applying the final sheet. The gesso has to be kept constantly warm during
this procedure in the pot with warm water, but it must never boil. The first layer of gesso is completely absorbed
by the wood. To apply the next layers you have to wait
until the gesso has mostly dried, otherwise it won’t stick as easily. You can continue with the second layer when
you can see that the gesso has become opaque. You’ll realize that with every layer the drying
time will decrease and the colour of the frame will become whiter. It’s always best not to try and accelerate
the drying process artificially, by putting it by a heat source, as this could provoke
cracking. At least 5 layers of gesso have to be laid
for the traditional gilding. For the mordant gilding just 3 are enough. Rinaldin suggests these brushes, which don’t
have the metal ring for applying the gesso. 24 hours after having applied the gesso we
can start with the sanding. A perfect sanding is important for the following
steps and for a good final result. An abrasive sponge can be used for this step…
or a wet rag (but not too wet)… or simply some sand paper. The abrasive brush which adapts itself to
the shape of the frame is suitable for simple surfaces like this one. Sand paper can be useful to smooth down some
points such as these. Rinaldin provides the following tools for
sanding gesso: Sand paper with 3 different grain sizes.
The biggest grain is needed for the first, “rough” phase. Sand paper with a medium grain is needed for
obtaining a smoother finish. Abrasive sponge with 3 different grain sizes. The thinner and more flexible sponge is suitable
for frames with a rounded shape. Also a damp rag is more than suitable for
sanding. The rag has to be frequently soaked in water
as the gesso tends to dry it quickly. You have to pay attention to not wet the gesso
too much, otherwise the small decoration details will flatten.
Furthermore be careful not to round the corners too much. When you’re finished sanding it’s best to
go over the frame with a cotton ball soaked in alcohol to clean it well and ensure that
there isn’t any plaster dust left. The application of the gesso on a frame with
an embossed design could make the shapes a bit rounder and therefore lose some of the
decoration’s details. In precise the parts that are hollow could
have filled up with too much gesso. In this case a reparation work has to be taken
into consideration. This process is done with special tools, so
called “repairing tools”. Before we can start with the repairing tools
it’s best to pass a damp rag over the areas which have to be worked on so that the gesso
becomes slightly wet, which makes working with the repairing tools easier. Then, choosing the most appropriate tool,
you delicately remove the gesso which has covered and rounded the decoration. Rinaldin provides these repairing tools:
On the top part of the photo you can see a complete tool and in the lower part the tip
of every tool is highlighted. You can find all the gilding products on the
website www.rinaldin.com

Dereck Turner

9 thoughts on “Gilding course: 1 – Gesso

  1. Stephanie Danvel says:

    Sorry not plaster it’s french chalk !

  2. Bluebuthappy182 says:

    I'm only the first lesson here but I'm thinking if i was a rabbit I'd be a little bit nervous. Excellent videos by the way.

  3. Nick Doe says:

    Wouldn't a paint work just as well today?

  4. Herman Hermitz says:

    Video is good but background music is completely unnecessary.

  5. Al Baba says:

    It's not plaster. It's powdered whiting!

  6. Al Baba says:

    No, the first coat is called colleta . It's a layer of pure rabbit skin glue. And it's usually more than five coats of gesso!

  7. Jennifer Delilah says:

    Hey, RINALDIN SRL, 
    It would seem as though you have hijacked the entire syllabus from www.pictureframes.co.uk. Every time I try to view a video of his, the next video that comes up is you. The only way this can happen, is if you have deliberately made his website a part of your search engine keywords. Knock it off.

    If the rest of you want to see a for real craftsperson, look at this guy:

    www.pictureframes.co.uk

  8. Britt Snapsters says:

    20 LBS OF GLUE?! FOR 20 G OF WATER? THAT'S A MISTAKE!

  9. Ariel Marcelo says:

    Q lástima q no está en Español!!

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