Whip Mix FireLite Specifications download pdf (Page 20)

18

Warning

The setting of gypsum materials

is seriously affected if they are

contaminated by phosphate

materials (CERAMIGOLD, HI-TEMP,

CERA-FINA Investments, etc.) or

alginate impression materials.

Therefore, the use of a separate

mixing bowl for each of these

types of materials is strongly

recommended. If properly cleaned,

the lids and paddles may be

interchanged although the use of

complete units for each class of

material is desirable.

The primary cause of aging of a

gypsum material is exposure to

moisture. Proper storage is therefore

important — a dry storeroom at

room temperature. When not in use,

containers should be tightly sealed.

Overstocking of gypsum materials

should be avoided. A six months’

supply is reasonable but more than

this could be excessive because of

the aging problem. However, material

in preweighed envelopes, because of

their moisture-proof design, should be

good for a much longer period. As a

guide for the user, all Whip Mix gypsum

materials show the date packaged on

the label.

To ensure our customers receive the most reliable and consistent products available,

Whip Mix tests every batch of gypsum for setting time accuracy, consistency, setting

expansion and strength.

Whip Mix Gypsums

Our Reputation is Cast in Stone

Physical Properties of Whip

Mix Gypsum Products

In order to help you choose the best

gypsum products for your needs from

our large selection, as many Physical

Properties as practical are listed. A brief

explanation of each property follows so

the gures will be more meaningful.

All Whip Mix products are tested in

accordance with ISO 6873. Certain

special products, made to t a specic

rather than a general need, are not

covered by the specication; for

example SUPER-DIE, MOUNTING

STONE, SNAP-STONE, etc.

Consistency

The ratio of water in milliliters to 100

grams of powder (water/powder ratio).

Proper proportioning of powder by

weight and water by volume is strongly

recommended.

Working Time

The lower gure is for mechanically or

vacuum-spatulated mixes at the lower

consistency. The higher gure covers

hand spatulated mixes at the higher

consistency. These gures denote the

actual time available for handling the

material after spatulation and before it

thickens and makes its use inadvisable

or impossible.

Setting Time ISO 6873

The Vicat Set obtained by the ISO 6873

test method is known as the Initial Set.

It does not correspond to any practical

value, as it is longer than working time

and shorter than “ready for use” — it is

rather an arbitrary method for testing

uniformity.

Setting Expansion

Obtained by the ISO 6873 test method,

setting expansion is reported at two

hours. Minor consistency changes will

not affect the value appreciably.

When casts are poured in alginates

or hydrocolloids, the gypsum product

will usually absorb a little water and

the expansion during setting will be

slightly higher. Whip Mix guarantees

gypsum products for two years from date

packaged.

Compressive Strength

This is another gure obtained by

the ISO 6873 test method. It is

determined on specimens maintained

in an atmosphere of 100% Relative

Humidity for one hour (also known as

wet strength). Compressive strength,

dry, is given as a general guide, no

standard method for this test has been

specied. The gures given are based

on specimens stored for one week at

approximately 50% Relative Humidity.

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