Question: HOW MUCH LATEX DO I NEED?

Results may vary depending on % solids, model surface, temperature and other variables, but here is an estimated coverage rate for latex:

The density of the latex is .92g/cc, and has a 30 in³/lb specific volume.

One pound of latex when dry only yields 19.2 in³/lb. due to evaporation.

One pound of latex at 1/16" yields 307 in² or 2.13 ft² 

Question: IF MY LATEX IS TOO THICK, MAY I USE TAP WATER TO DILUTE THE LATEX?

Tap water is not a very good thinner for latex since it may contain Calcium and Magnesium salts.  Even small amounts of the salts of Calcium and Magnesium have a tendency to coagulate the latex. Hard water must never be used.

Question: WHAT IS BEST TO USE TO THIN LATEX?

If you wish to thin out the latex, simply use distilled water or bottled water. Read the label carefully, several bottled waters contain calcium.

Question: HOW CAN I THICKEN THE LATEX TO FILL IN DEEP UNDERCUTS?

Use CECO Powder.  It will thicken the latex to a point where it can be applied with a trowel.  It will also strengthen the latex.  Only mix CECO Powder in backup coats after the first few coats have been applied.

Question: HOW LONG SHOULD I HEAT THE RUBBER TO COMPLETE THE PROCESS OF VULCANIZATION?

Vulcanization is the combination of Latex with Sulfur in the presence of heat. If a rubber is not vulcanized, it has poor keeping qualities and usually does not keep its original form, especially upon stretching. We recommend 24 hours at 100-120 degrees Fahrenheit or 38-49 degrees Celsius.  Or, let it stay at room temperature for about 4 days.

Question: WHAT EXACTLY IS VULCANIZATION?

Vulcanization is the combination of various ingredients with the rubber under controlled heat to create a flexible elastomer.

Rubber that is not vulcanized is usually hard under low temperature and very soft at high temperature. Un-vulcanized rubber is also "tacky", and when stretched, deforms very easily. Un-vulcanized rubber shows "plasticity" as opposed to "elasticity".

Vulcanization corrects these defects while greatly increasing the tensile strength of the rubber.

Question: WHY DOES LATEX HAVE AN AMMONIA SMELL?

Ammonia preserves latex and is also an anti-microbial.

Question: WHAT IS THE SHELF LIFE OF NATURAL LATEX?

When properly stored at room temperature (73°F / 23°C), Holden's Latex Rubbers will have a shelf life of 12 months from date of manufacture in unopened containers. Important: Latex must not be allowed to freeze.

Question: HOW LONG SHOULD I WAIT BETWEEN COATS OF LATEX?

Our products are designed to be coated about every hour.  This is not a hard and fast rule and judgement is required.  You do not have to wait a few hours between coats.  However, avoid waiting more than 25 or 36 hours between coats.

Question: MY BRUSHES DRY WHEN I COAT LATEX ON MY MOLD.  WHAT SHOULD I DO?

Keep several inexpensive brushes in thick,soapy water.  Use Ivory liquid soap or Murphy's oil soap, or something similar.  Remember that latex dries by the evaporation of water, so, naturally, your brushes would get all "gummed" up.  Remember to shake your brushes out well before you begin coating.

After your brush gets stuck, place it back in the soapy water and switch to another brush.  Comb your previous brush out with a fork or dog comb.  If you still have dried rubber in your brush, soaking the brush in lacquer thinner will help.

Question: WHAT DO I DO IF I GET A BUBBLE OR A BLISTER WHEN I AM BRUSHING ON THE LATEX COMPOUND?

Burst the bubble with a pin or use a syringe to withdraw the air.  When brushing, brush up and down and left to right.  This helps burst the bubbles.  Then simply continue brushing.

Question: HOW DO YOU REPAIR A NATURAL LATEX MOLD WHEN IT TEARS?

The best method we found is to lightly abrate the area, and clean the area with acetone or alcohol. Then brush some UreCoat™ from Smooth-On on the tear, take some gauze or other stretch fabric and push into the wet UreCoat™ then encapsulate fully in UreCoat™. This will create a strong flexible repair to the original latex.