Molding and Casting
Group Assignment 2021
Silicone for food
One of the materials that we are going to document in the group work is a silicone to make food molds. Of the silicones that exist on the market, we are going to use the: EASYL 940-FDA.
EASYL 940-FDA is a two-part silicone, platinum-cured or addition type, with a mixing ratio of 1A: 1B in volume. It can cure at room temperature and also under heat.
As main recommendations for use:
■ Good ventilation.
■ Wear waterproof gloves, such as butyl rubber, neoprene, or PVC.
■ Safety glasses with side shields.
link feroca
https://www.feroca.com/documentos/SILICONAS_ALIMENTARIAS.pdf
https://www.feroca.com/documentos/FT_EASYL_940_FDA.pdf
https://www.feroca.com/documentos/HS_EASYL_940_FDA_ES.pdf
ACMOS 82-2405 RELEASE AGENT.
*** Warning: I do not use mold release agents in my work. The silicone came off easily as it was flexible. If this is used, the food use of the mold is lost. With this silicone, a mold release agent can be used. It serves to prevent the food grade silicone from sticking excessively to your wax mold. In this way it can be easily removed from the mold.
This complement to unmold the silicone, is a little more dangerous, according to the technical data sheet.
Hazards:
■ Extremely flammable.
■ Irritating to skin.
■ Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment.
■ Vapours may cause drowsiness and dizziness.
The general recommendations for using the mold release agent are:
■ Good ventilation.
■ Use only chemical protective gloves with CE marking category III according to EN 374.
■ Safety glasses with side shields.
FEROCA LOW COST SILICONE
Feroca Low-Cost Silicone is a two-component silicone elastomer (parts A and B) that cures at room temperature, the base (part A) has the appearance of a viscous liquid which, after the addition of the catalyst (part B ), becomes an elastic material. It features exceptional fluidity and good operability. It is recommended for the application of molds for casting of Plaster, Polyester Resin, Polyurethane Resin, Epoxy Resin, Fiberglass, Wax, Soap, Bronze, etc. It is a type of soft silicone rubber with medium viscosity, so if desired you can lower the viscosity using Silicone Fluid. It is suitable for molds with complicated gaps that are difficult to remove from the mold.
INSTRUCTIONS:
■ Prepare the box for the mold and the original.
■ Set aside 100 parts of the base (Part A) and add 2 parts of catalyst (Part B), mix both parts VERY well until a homogeneous mixture is achieved.
■ Pour the silicone wash into the box or apply with a brush if it has been previously thixotroped.
■ NOTE: Normally, low hardness silicone is used for casting molds, as it allows a better demoulding and thus does not damage the original.
■ Wait 15 hours for the silicone to solidify and remove the mold.
Silicone page for the mold
Low Cost Silicone Datasheet
Safety data Sheet Part A:
Safety data Sheet Part B:
SMOOTH-CAST ONYX FAST
Smooth-Cast™ ONYX™ is a mercury-free urethane resin that cures at room temperature to a deep black, solid plastic. ONYX™ resins offer the convenience of a 1A:1B by volume mix ratio and have very low viscosities, so they are easy to mix and pour. ONYX™ resins have an ultimate Shore hardness of 80D and offer higher physical properties and higher heat resistance vs. other general purpose resins.ONYX™ FAST resin has a pot life of 2.5 minutes and a cure time of 10-15 minutes. ONYX™ FAST is a good choice for creating fast cold cast bronze, brass, copper, nickel/silver, etc. effects.
Smooth-Cast ONYX page for the mold
Safety data Sheet
Features:
■ Ultra-black and darker than competitive black resins.
■ Can be polished and buffed to a high gloss shine.
■ Higher heat resistance vs. competitive black resins.
■ Does not contain mercury.
■ Less expensive vs. other black resins.
Mixing - Pre-mix Part-A and Part-B thoroughly before you begin. After pre-mixing both parts, dispense required amounts of Parts A and B into mixing container and mix thoroughly. Stir for at least 60 seconds.
Pouring into the mold should be done as quickly as possible, you have less than 2 minutes to fill the mold because it solidifies quickly. Be careful because an exothermic reaction is generated and the plastic cup will heat up.
Post Curing - Although not necessary, post curing will increase physical properties, material performance and heat resistance to 250°F/121°C. After curing at room temperature for 1 hour, expose material in the mold to 250°F/121°C for 4–6 hours. Let cool to room temperature before use.
VYTAFLEX 40 URETHANE RUBBER COMPOUND
IMPORTANT: Premix Part B before using. After applying amounts equal parts A and B in the mixing bowl, mix well for at least 3 minutes scraping the sides and bottom of the bowl several times. Hardening: Allow the mold to harden for at least 16/24 hours) at room temperature (73 ° F / 23 ° C) before removing from the mold.
Extra Harden: Optional ... After allowing to harden overnight, heating the rubber to 150 ° F (65 ° C) for 4-8 hours will improve its physical properties and its performance.
VytaFlex40 page for the mold/a>
Safety data Sheet
DataSheet spanish
SILICONES USED IN MOLDS:
Food Silicone 940-FDA Vs LOW-COST SILICONE FEROCA:
When it comes to working with 940-FDA food grade silicone, there is no potential danger that could be very harmful. But it is necessary to have minimum security such as using a ventilated place, wearing glasses to protect the eyes against splashes and gloves.
We have used it without a mold release agent, because we did not need it, it extracts very well from the wax mold.
It has the advantage that it can be used with food material and the product obtained with the molds with this 940 FDA silicone can be edible without being harmful to the user.
With LOW-COST silicone, it is also advisable to work in a ventilated place, wear glasses and gloves. It is not a very harmful silicone for the user so it does not pose a risk to the user, as long as it is used with the mentioned protections and with care.
The disadvantage of this silicone is that it can only be used for parts that are not intended for food use.
Furthermore, neither of the two silicones is harmful to aquatic environments.
If the results for the molds created with these silicones are compared, food grade silicone is colorless and its mixture is slightly less viscous than LOW-COST silicone. This allows it to be poured a little faster. The bubbles that are generated when mixing the components of the silicone are very small, some come out, but many remain trapped. Being small they have not been a problem for our molds.
Referred to LOW-COST silicone, it has a white color, its mixture is a little more viscous and it must be poured at a slower speed. The drying time is approximately the same as that of food grade silicone and it is advisable to cure for a few minutes in the oven.
The finish is similar to food, although for our results, it has a slightly worse surface finish than food. Possibly, because with this silicone the bubbles are extracted a little worse because it is a little more viscous.
MATERIALS USED TO CAST, FOR THE PARTS:
Smooth Cast ONYX Fast:
It is a mercury-free urethane resin that cures at room temperature and is black in color. It has a very low viscosity, lower than the previously mentioned silicones used to make the molds. It is easy to pour and mix. You have not created bubbles in the final piece.
As a drawback, you have to control the mixing time very well and pour a little quickly in less than 2 minutes since its useful life is about 2.5 minutes and it cures very quickly. You also have to be careful, wear gloves, glasses and for example a lab coat in case it splashes as it is a bit dangerous, because it generates an exothermic reaction.
As an advantage, it is very hard and has a very good finish, although if it does not pour well, it can create imperfections and deformations.
VytaFlex40:
It is a type of liquid urethane rubber, it has the possibility of being acquired with various hardnesses, 10,20,30,40,50 and 60. It has a useful time of 30 min so its use is more comfortable and less stressful than that of the old resin in which time had to be controlled very strictly.
Care must also be taken when handling it because it can irritate the skin, so use gloves and apply in a ventilated place since the components emit vapors. In addition, it is necessary to wear glasses to protect the eyes.
This type of rubber is more viscous than Smooth Cast resin although as it has a longer useful life, it is easier to make it reach all parts without problems.
It has the advantage of being able to create flexible and elastic pieces with a very good finish. Give an example in the case of Gustavo, it is very good for the handlebar of the skate.