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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