Quartz sand (AFS number 35)

Description

Fine Quartz Sand for Water Glass Process

– Fine quartz sand for mold making
– min. 99.5% SiO₂
– Density: 2.65 g/cm³
– Bulk density: 1.40 g/cm³
– Melting range: > 1,560°C
– Grain shape: sub-angular
– AFS number 35
– MK 0.44

The sand is suitable for building molds and cores for metals and alloys with melting points up to 1300°C. Its fine grain size enables a relatively smooth surface quality.

We recommend using the water glass process primarily for building cores. These can be easily used in combination with oil sand or water-bentonite bonded sand. With oil sand and water-bentonite sand, you achieve higher surface qualities than with the water glass process. Additionally, the materials used and reusability are significantly more cost-effective with oil sand and water-bentonite sand, or even possible at all. As a core process, however, the water glass process is generally better suited because no mechanical compaction of the sand is required to ensure strength. Light compaction is sufficient, as the main strength is achieved through chemical hardening.

For the hardening process, the sodium silicate binder TZ19 is required in any case. For this to work subsequently, either CO₂ gassing must be applied or hardener W20 must be used. A combination of both hardening agents is also possible but usually not necessary.

 

For use:

Measure the required sand volume and fill the quartz sand into a mixing container.

Next, add 3–4% of the sand mass of sodium silicate binder TZ19. Stir this in for approx. 2–3 min. so that it distributes evenly in the sand.

If you are working with CO₂, then form the sand into the desired shape and optionally pierce small, thin holes into the sand. These facilitate CO₂ absorption and ensure better through-hardening. Now expose the core or mold half to CO₂ gassing and ensure that the gas does not escape, e.g. by flooding a closed container with CO₂ and then covering it. CO₂ is denser than air at room temperature. The hardening process takes approx. 20–30 min, depending on the thickness of the core, possibly less or somewhat longer.

If you want to use hardener W20 for hardening, mix it into the sand after mixing in sodium silicate binder TZ19. Use approx. 0.5–1% hardener W20, based on the sand mass. Mix preferably during addition or immediately afterwards. This prevents clumping and ensures even distribution of the hardener. Mixing should also take approx. 2–3 min.

After mixing, put the sand directly into the desired, already prepared mold, distribute it evenly, and press it down lightly. Here too, optional CO₂ gassing can be used to achieve optimal strength; however, this is generally not required. Hardening takes approx. 20–30 min; after that, the core or mold half should be sufficiently firm.

For very thick cores and molds, it can be useful to use both hardener W20 and CO₂ for hardening to ensure optimal through-hardening.

After CO₂ gassing, or after placing it in the mold following mixing with hardener W20, avoid further changes to the shape. These destroy the chemically formed bonds between the sand grains and reduce the sand’s strength.

After casting and demolding, the sand unfortunately cannot be reused without further processing. Thermochemical processes are required to remove the sodium silicate bond, which are generally not feasible on a small scale.

You can also obtain the following necessary auxiliary materials from us:

Sodium silicate binder TZ19
Hardener W20
5 L mixing bucket
Whisk set for mixing
Talc

The complete set for producing molds using the water glass process includes:

– 25 kg fine quartz sand
– 1 kg sodium silicate binder
– 500 g hardener W20
– 1 kg talc
– 1x dust bag
– 1x three-piece whisk set
– 1x sturdy 5 L mixing bucket
– 1x 100 ml measuring beaker

Additional information

Information on the base price:
Since these are tiered prices, the base price corresponds to the total price for the respective weight/dimension.

Coupon codes

• m100 (2% discount, redeemable for order amounts from €100-€299.99)
• m300 (5% discount, redeemable for order amounts from €300-€599.99)
• m600 (10% discount, redeemable for order amounts from €600)

*Volume discounts can be redeemed in the shopping cart using the codes provided