Additive to be added to a 1:4 shellac weight to alcohol volume mix. Cross links in about 20 days and forms an extremely tough final coat.

• 40gms to 250ml
• 81 gms to 500ml
• 161 gms for 1 litre

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Notes updated January 2021

HARDENER FOR SHELLAC SOLUTIONS.
(Note: From early 2016 this product has been formulated to allow use in any portion desired provided the mix ratio is carefully adhered to. In other words the several components in the solution now decant and maintain proportion).
 
After shellac has been dissolved in ethanol it is possible to introduce this additive which causes the shellac to cross link over a period of about 20 days. Note that this crosslinking process can be shortened within reason by 2.5 days for each 10 degree Celsius increase in temperature with lights or a heater. It follows that a polishing project should be completed comfortably within the 20 days timeframe where chemical bonds still remain for the crosslinking to occur.

This additive has been mixed to be appropriate for maximum hardening. It is added after the shellac has been put into solution. The hardened shellac can be used on table tops so that tendency to condensation & heat rings are mitigated or eliminated. Also increases resistance to alcohol.

The additive must be in intimate contact with the shellac solution for 72  hours before the hardened shellac can be used. Application gear must not be allowed to go dry otherwise brushes, rubbers & spray nozzles will go rock hard. Wash them out well with metho. For heat resistance on window frames, tables etc, every coat should be with the hardened shellac.

For damaged pieces finished with conventional polish which are required to be re-finished with hard shellac the old polish should be removed prior to replacement with hard grade. For similar reasons which apply to mixed coats of waxy and de-waxed polish, hard grade polish coats should not be mixed with conventional polish coats due to the differrential hardness which can result in crazing.

Process of application & coating intervals of hardened shellac is identical to unhardened shellac. When using a rubber (aka Fad or Tampon) apply some oil on long strokes to prevent tearing. This additive slightly slows the drying process which reduces blooming & allows for a brush to be used on large surfaces without the "edge" drying before you have time to get back to the start point.

SHELF LIFE - Hardened shellac can be treated as non hardened shellac for the purposes of shelf life. We recommend waxy grades - orange and button - should be used within 24 months of being made up and the de-waxed blonde, ruby, garnet and white grades within 18 months.  Refrigerate both flake and made up polish. Shellac is an organic product.  Do not freeze.

MIX RATIOS - This product assumes you are starting with a polish made up to a 4:1 ratio weight of flake to liquid volume of alcohol (e.g. 1  kilogramme flake to 4 litres of alcohol or 2.2 pounds of flake to 1.05 gallons of alcohol).  For a 250ml mix put 40 grams of hardener in the container and top up with the 1:4 shellac mix
For a 500ml mix put 81 grams of hardener in the container and top up with the 1:4 shellac mix etc

Allow 72 hours for the made up hardened mix to mature before use

THINNING  - When the hardened shellac mix is made up as advised above it can then be thinned as desired for use. The use of 100% denatured absolute alcohol (DAA spirits on the Australian market) or IMS  (Industrial Methylated Spirits  - usually specified to be 95% proof) is strongly recommended. Hardware store methylated spirits may contain unacceptable amounts of water which can cause blooming in the finished work.  

CLEAN UP - Note that the common practice of leaving polishing brushes loaded with polish and uncleaned between work sessions cannot apply to hardened polish as brushes will go rock hard and not be restored for use.

TOUCH UP & RESTORATION - Hardened shellac cannot be treated as normal shellac for touch ups and re-coats. In this respect it is similar to other catalysed varnish finishes. Re-coats outside the 20 day application window will not meld with the older polish.  Scuffing the old surface to form tooth may be attempted.

TOXICITY - Given that the ethanol has off-gassed this hardener does not affect the toxicity of the shellac base which is rated as food safe and widely used as a pharmaceutical, confectionery and fruit glossing agent. It is rated as a food by the US FDA.

DOMESTIC ORDERS - Have to ship via road courier and require a physical address and delivery instructions

EXPORT ORDERS - This product is only available for domestic Australian orders.

RELATED PRODUCTS

• Ondina oil for lubrication HERE.
• Brushes HERE
• Pumice HERE
• French polish & Shellac data sheet HERE