Around half of the Smiths CPES sold worldwide is used as a varnish primer on new wood. It is so effective at that purpose that you can achieve 20 years before you have to sand back to bare to refinish your varnish. If you have ever had a varnish finish fail early you will know how big a claim that is, not utterly permanent – but as close as you will get. Read this testimonial for more details: 20 year varnish finish on a wooden boat.
Benefits Of CPES as Varnish Primer
Smiths CPES will:
- Penetrate the outer fibres of the timber – leaving them waterproof yet breathable
- Leave a hardened yet flexible surface on the timber. This is far more durable to everyday knocks than even epoxy glass sheathing, as it flexes rather than cracking when hit. Consider your freshly varnished yacht mast – and the metalwork that may ping off it on the end of a rope
- Protect and consolidate the top fibres of the wood – leaving a firm base for your top coat
- Physically glue the topcoat down to the wood with epoxy strength
- Seal the edges of your plywood or the end grain of your timber like nothing else can
- Prevent the varnish lifting from the wood banishing unsightly white spots and early refinishing
The worlds best spar varnish is generally considered to be Epifanes. If you have never used it before – perhaps you should treat yourself and your wood.
Coverage Of CPES as Varnish Primer
CPES (which is sold as MultiWoodPrime in America for this purpose) will cover at approximately the following rates when used as a varnish primer applying two coats:
|Material||Sq metres / Litre|
You should be applying varnish at approximately 1 Litre per 2 Sq Metres initial coverage.
The following table may help you to estimate how much CPES Varnish primer and Epifanes to order:
|Material||Area||Litres CPES||Litres Epifanes|
|Hardwood||10 Sq M||1||5|
|Hardwood||5 Sq M||0.5||2.5|
|Hardwood||2 Sq M||0.2||1|
|Softwood||10 Sq M||2||5|
|Softwood||5 Sq M||1||2.5|
|Softwood||2 Sq M||0.4||1|
|Plywood||10 Sq M||2||5|
|Plywood||5 Sq M||1||2.5|
|Plywood||2 Sq M||0.4||1|
The application of Smiths CPES varnish primer is covered here: Smiths CPES
The application of the varnish is covered here: Apply varnish properly
A complete how to do it, with photographs is covered here: Restore exterior wooden sign to last beautifully
Ultraviolet (UV) Light degrades varnish. Sunlight is the strongest common source of UV light. However LED and fluorescent lighting also generates smaller amounts of UV Light. Consequently you will have to add additional coats of varnish every year or two as appropriate. The amount and frequency of adding varnish will depend on the exposure to UV light. The UV blockers in varnishes are not UV stable by their very nature. Maintaining UV protection will keep the wood and CPES in good condition. The Smiths CPES will keep your varnish stuck to the wood.
You will have to clean the surface and provide a key with gentle sanding (400 grit or similar) prior to applying the new layers of varnish.