PROPER MOLD CARE

To extend the life of your molds here are a few tips on how to care for them.  All molds must be kept clean and free of debris.  The pouring surfaces must be protected from scratches or gouges which will appear as defects in the concrete product.  Molds, of any material, should not be dropped, thrown, hammered, or bounced.  If demolding becomes difficult it is usually not the mold at fault.  If the mold is clean and free of residue demolding should remain constant and relatively easy.  To clean your molds a solution of warm soapy water and a soft brush is very effective.  On fiberglass molds muratic acid may be used.  Also on fiberglass and steel molds that become stubborn a proven method to aid in release is wax.  After the mold has been thoroughly cleaned apply two coats of a quality car wax.  According to label instructions.  The mold will still require the normal use of a release agent after waxing.  The wax will fill and smooth microscopic imperfections in the mold which concrete tends to grip.  The wax application should be done every six to eight weeks or as needed depending on frequency of pouring a certain mold.  Latex rubber molds have their own unique characteristics.   Latex molds will at times absorb moisture from concrete.  This causes the latex to swell and become too large for the fiberglass backing.  The cure is simple.   For two days out of seven, across the weekend usually, leave your rubber mold open out of its backing.  Place in a ventilated area and allow it to dry out before reassembly.  This is generally only necessary on molds which you pour every day during the week.  A word of caution.  Do not store, pour, or ventilate latex molds near or on fiberglass, steel, or ABS plastic molds.  The reason for this is that contact between the latex and any petroleum product, such as release agent, will cause a rapid deterioration of the latex.  It will soon become totally unusable and will have to be replaced.

MOLD RELEASE

To allow a finished concrete piece to be more easily demolded a release agent is applied to the mold prior to pouring.  There are many different types and brands to choose from.  There are two important factors to remember when choosing a release agent. 

1) There are different types of molds.   This is in reference to the material from which the mold is constructed IE steel, fiberglass, ABS plastic, latex rubber. 
2) Some mold materials need to be seasoned before use and all require an occasional thorough cleaning.

For molds made of latex rubber, from Nunnikhoven Group these come with a fiberglass backing or outer shell, a non-petroleum base product is needed.  We recommend a mixture of 1 part caster oil to 8 parts methanol alcohol.  This is a long proven reliable release agent for latex molds.   You may also choose one of a variety of commercial products on the market.  Be sure they are specifically for latex rubber molds poured with concrete.

Steel, fiberglass, and ABS plastic molds require a petroleum based release for best results.  Fiberglass molds must be seasoned prior to pouring.  To season these molds release agent should be applied and allowed to dry three to four times over the course of two to four days.  The mold should then be wiped clean of any excess residue and have release agent applied just prior to pouring each time in the future.  We recommend Cast-O-Magic from Rostine Manufacturing as a release agent for these three types of molds.  The choice is yours however to use whatever works best for you.  The home-made formula for release agent, for these molds is 50% motor oil and 50% diesel fuel.  Caution here because it may cause staining of finished concrete if improperly used or if inferior products are used to make this release.

Please also note that in many instances the first one or two pours of a new mold, of material, may not yield a good piece.  Give it a chance and by the third pour you should have want.

Alcohol based release agents should never be used on plastic or fiberglass molds deteriorate them.