Fatti non foste a viver come bruti...

[Calvin]

...ma per seguir virtute e canoscenza. (Dante, Inferno XXVI) Which can be freely translated as "you was not made to live as brutes, but to follow virtue and knowledge".

I think Dante was a very interesting guy. Born in 1265, when he was 12 year old, his family planned his marriage with Gemma (a common practice for that time). Dante had several sons with Gemma, but his true love was Beatrice (a girl he only saw in three occasions). In 1289 he took the side of the Guelfi against the Ghibellini (the two factions of Firenze), participating to the battle of Campaldino (against Arezzo) and Caprona (against Pisa). Appointed as a Priore of Florence (one of the six chiefs of the town), in 1302 he was forced to the exile. A tentative to take again the city of Firenze, leading the troops with Scarpetta degli Oderlaffi ('Signore' of the city of Forli') was unsuccessful. He died in Ravenna in 1321.

A poet, but also a true fighter, without no fear in taking the arms when needed. The official image is a bit idealized, so I prefer to think about him like a very strong and determined guy, able to stand and live with his responsabilities (like the unwanted marriage with Gemma or the charge of Priore), and ready to give a good trashing to his enemies. This way, such sentences like the current topic title could also be interpreted as "I'll explain you the way, but if you do not want to understand, I can use a more effective way...", a bit more more tuned with those hard times.

Well, all that to introduce my next, a bust of Il sommo. Finally, I managed to replicate some skeletons I made for the head.

the originals

the one piece mould

and the casted pieces

Using one of the above head as skeleton, this is just a sketch of the head for the Dante bust (1/10 scale, the head is aprox. 2,2 cm).

It's just the base, a lot of work to do.

 

[garyjd]

Luca, Very nice sbs. I like the head you are working on. It's strange that he almost resembles Charles XII of Sweden. I can't wait to see more.~Gary

 

[Calvin]

Well, to be honest there are a lot of pictures of Dante, but every portrait I found differs a little from the others. The only thing which seems to be constant is that the central part of the face (nose) is bigger than the upper (front) and the lower (chin).
The distance between the extremity of the nose and the upper lip seems lower than the standard, while the eyes are generally portrayed as smaller and more separated than the normal.

There is also a death mask of Dante available on the web, at http://libweb.princeton.edu/libraries/fire.../C0770/d-k.html, from the Princeton University Library:

but considering that is a death mask, I suppose it portraits an old man, so I'm using it only as a guideline, for a mature version of Dante I prefer to use a mix from my grandparents:

The first (Umberto) perfectly matchs the Dante death mask, but the second (Amico) is the one who better reflect such strong character (at least for me).

Now, achieving a realistic result is another story... :lol:

 

[garyjd]

WOW! I love the process you are using to develope the character.~Gary

 

[Markus]

Hi Luca,

that looks pretty intersting. I like the charakter of the face and the nose!!

I´m looking forward to your next steps.

Ciao,
Markus

 

[Cicero]

You're a great artist, Luca. Can't wait to see this bust finished!


Johan

 

[Calvin]

Thanks Markus and thanks Cicero you are too kind, but this is too much for me...

Not so many time available, so there is just a poor advance. The face is not finished yet, I need to adjust the eyes and the lips, while the torso is just outlined.

Lately, I spent most of my spare time playing with the casting stuff. I'm not an expert (this is just my first attempt), so do not take it as a reliable tutorial.
Moreover, most of the casting products are toxic and/or could produce allergic reactions, so you are always using them at your own risk. Do not eat, drink or smoke while handling such products, always wear protective gloves and glasses and handle them in a very well ventilated area.

For what I see, there are basically two classes of silicone suitable for moulds, the standard, coming with the catalyst agent, to be used with a percentage from 5 to 10, or the one used by dental laboratories, a two components silicone with a 1:1 mixing ratio.

Choosing between local products, for the first category I found the one from Feroca. Is a standard type mould silicone, with a catalyst agent to be mixed in a ratio of 5%, with a shore of 13, up to 1 hour of working time and 24h of curing time.

The main issue with this type of product is the very long curing time and the air bubbles, a lot of air bubbles which appears during the mixing stage. Also, mixing a transparent catalyst in a rate of 5% with white silicone makes really hard to understand when the silicone is ready to be poured.

The other class of silicone (my preferred) is the one used by dental laboratories. A bit more expensive in respect to the standard (above) type, is a two components silicone (generally one white and the other blue), to be mixed in a ratio of 1:1. The one I found here is probably the best on its category, is the Dupliflex from Protechno, with a shore of 18, 30/60 secs. of mixing time, 5 minutes of working time and 30/40 minutes (not hours...) of curing time.

When mixed, is a very fluid (and not so sticky) product, air bubbles are almost non-existent an you can easily notice when the product is ready to be poured.

 

[Calvin]

By the way, shore is the scale used to measure the hardness of such products.

To make a two parts mould, I prefer to use the Scuper Sculptey instead of the usual plasteline, it's much more easy to work, not so dirty as the plasteline and does not sticks to the master.

Of course, it must be used without baking it...

This is my second two valves mould. My laziness prevents me about doing a more appropiated and shaped box, so I was using an oval spaghetti packet (made of plastic), cutted as required. The result is a bit naif and requires more silicone than the necessary, but it works...

and this is a close up of the mould, made using the standard type silicone.

to obtain an almost bubbles free surface, the silicone was poured by very thin layers, shaking the mould, etc. More than one hour of work...

 

[Calvin]

On the other side, this one-piece mould was made using the dental silicone in the worse way (just to do a test), poor mixing, no caring about air bubbles, no caring with pouring, etc., BUT this is the result, a beautiful, almost bubble free mould.

After this test I decided to use it as required, so these are the steps. First the box for the one-piece mould

next a careful measuring and mixing

and finally the pouring

almost every silicone is affected by environmental conditions while curing, a cold and humid ambient is to be avoided, so here a little trick to ensure a good set

Et voila!

the mould now ready.

 

[Calvin]

As you can see, making a mould it's very easy, the fun begins when you need to cast the piece, pouring the resin...

There are a lot of resins, the best you can use is the polyurethane resin. Generally the mixing and working time of such resins is really short (from 30 seconds to 5 minutes), so you need to work fast as the light. This is the 2 minutes resin from Feroca

a very good one, with a light sand/buff colour, while this is the 7 minutes resin from Smoot-On (white colour), my preferred.

I've no vacuum or pressure chamber, so I need to work almost drop by drop, using a syringe and shaking the mould while pouring, but I'm very satisfied with the final result, a pratically bubbles free casting

That white is not my preferred colour, but I think it can be adjusted using some pigment. It's true that the original piece is very simple, but for more complex masters you can pour a first layer of resin in every valve of the mould, couple the mould and finish the pouring.

That's all, now getting back to my Dante bust...

 

[megroot]

Thanks Luca,

This is a great SBS. How long is the lifetime of the resin when the cans once opend??

Marc

 

[Calvin]

Thanks Marc,
it depends from the manufacturer (the Smooth-on packages, for example, comes with a detailed reference sheet), anyway every time you open the can the resin will absorb humidity from the environment (which degrades it), so as fast you use it, better results. Moreover, most of resins needs to be shaked before using them, which adds the air bubble problem.
For what I see (just from my empirical point of view), after shaking and opening the can, the best you can do is to pour the required amount of each component in a separate cup, leaving them on the upper of a radiator for 5/10 minutes (until air bubbles disappears), before mixing the them. Also, warming the mould seems to help when pouring. Note that a (radiator) temperature of 25/30º will be enough (at least for me).

 

[garyjd]

Luca, You should be very pleased with your results, being it the first time you ever cast anything. The castings look clean considering you are not using a vaccum chamber or pressure pot to rid the resin of any trapped air.~Gary

 

[Manfred]

Great work on the face and the skulls.

And thanks for giving your thoughts and pictures on sculpting.
I use a blue silicone like yours and don't have problems with it, nice to work with.
However resin casting is more difficult. I use syringes and dust some talcum into the mold which seems to improve resin flow a bit but will try your tricks next time.

A question: When you do one piece molds, don' t you fear damaging the master when cuttinig it open ? And how do you keep it aligned ?

 

[Calvin]

Hi Manfred,
I'll try your tip about talcum, the main issue I've at the moment is about eliminating the trillion of air bubbles I get when shaking the resin before mixing.

Basically, a simple elastic band is the only thing I use. I think it works because the shore factor and the high quality of the silicone from Protechno. As you can see, there is nothing more.

This is a three cuts, one-piece mould. It would be better to make a zig-zag cut, but also a linear cut works well for me in this case.

I've marked the cuts with a black pen, but with that silicone is almost impossible to see them.

To avoid any damage to the piece, I use a two pass cut. Make a first cut without reaching the piece. Separe the silicone with some tool and go with the second cut.
This way, when opening/separing the first cut, due to the softness of the silicone, you will see the surface of the master, so a simple touch with the cutter (the second pass) is enough to cut the silicone without touching the piece.

I do not use sophisticated tools, just surgical blades and pliers

If you need to make a non linear or zig-zag cut to follow the shape of your piece, just place some needle in the box for the mould before pouring the silicone (imagine that the yellow lines are the neeldes, piercing the box and touching the master)

This way, when you have poured the silicone, the extremity of the needles which remains out of the box, will mark the cut line.

 

[Anders Heintz]

Excellent SBS Luca!

Love the way your Dante is shaping up as well as the casting tutorial.

Looking forward to the next installment!

 

[Manfred]

Thank you for elaborating Luca

Now even I understand the cutting process :lol:

 

[fsdesimone]

Good to see you hard at work Luca.

Francesca

 

[Roc]

Ciao Luca, great step by step, very informative, thanks for posting.

Cheers
Roc.

 

[garyjd]

Luca, thanks for the sbs on casting. Might have to try it one day just to at least say I had done it once. Thanks again.~Gary