Xylene:paraffin Solution
The xylene dissolves the secret 15% component in Additive F, or the paraffin under discussion – xylene creates the carrier solution. This would produce an even dispersal throughout the mixed epoxy.
In theory, as the epoxy polymerizes, forming cross links, the paraffin could be excluded from the the molecular lattice. This might push the paraffin to the surface as a very thin layer – xylene would volatilize. The remaining thin surface layer of paraffin might protect the epoxy surface from humidity during curing. However, I question whether bonding with the next coat of resin would not be compromized by paraffin.
Additive F
According to Greg Loehr:
In laminating, (Additive F) it helps wet the cloth eliminates most air bubbles, especially around wings and boxes, reduces the amount of resin needed, and most of all eliminates blush. Blush is what causes the banana peel effect you were referring to. In hot coats it eliminates blush, fish eyes, other surface blemishes and increases Barcol hardness. This increase in Barcol makes the board sand easy and improves the bond and strength between layers.
Amine Blush
Web definitions:
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This was written well enough. I see no point in writing a summary:
http://www.yachtpaint.com/usa/diy/ask-the-experts/what-is-amine-blush.aspx
What is amine blush?
When using a solvent free epoxy resin... **After application and during the curing (drying) process, the epoxy releases a blush to the surface called ‘Amine Blush’.** This blush is known to appear as a ‘wax-like’ film that sits on the surface of the cured epoxy resin. This amine blush will in fact keep some subsequent products applied from fully curing, performing correctly and also yellowing unless removed properly. The visibility of the blush will be determined by the moisture in the air during the curing process, however will still be on the surface if not always visible. **The best way to reduce blushing is to work in warm temperatures (the epoxy sets up fast, reducing the blush window) and with humidity at low levels. It would be best to avoid conditions where moisture is coming out of the air as temperatures fall.**
How to remove it?
Interlux recommends thoroughly washing the cured epoxy with clean warm water, all-purpose soap, and a stiff brush or Scotch-Brite™ pad. The amine blush is water soluble therefore the only way to completely remove this is by following the instructions above. You will want to clean the amine blush off of the epoxy before sanding as well. **If you begin to sand before removing the amine blush, you may sand the blush deeper into the surface making it much harder to remove. **It is a safe practice to clean all types of epoxy resin, even if the label states that it is ‘amine blush free’ or ‘no blush formula’. Please note: **Aggressive solvents like Acetone will not remove the blush.**
What will it do to my project?
**If amine blush is present on the surface and is not properly removed, you might not notice a problem with your project until after it is completed.** If you use a single-part primer such as Interlux Pre-Kote and do not remove the amine blush, the blush will migrate through the Pre-Kote to the top of the surface causing the Brightside® single-part polyurethane finish to improperly cure from the contaminated areas. It could also lead to detachment of both primer and finish. ... **Some epoxy resins can take up to 2 weeks to fully cure, still releasing amine blush to the surface. **
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http://www.westsystem.com/ss/assets/Uploads/Ew20Contamination.pdf
However, most adhesion problems can be traced to some form of surface contamination.
Amine blush may be formed when epoxy cures. Amine blush is water soluble. Many organic solvents are completely ineffective for removing it. That is why we suggest washing an epoxy surface with water (water clean enough to drink) using a Scotch Brite™ pad (or wet sanding with waterproof wet/dry sandpaper) and drying it with paper towels before continuing with another operation. Soapy water, or water with ammonia or bleach, is not necessary and may leave a residue—another possible surface contamination.
_____http://www.polymer-services.com/AMINE%20BLUSH%20v2.pdf
Amine-cured epoxy formulations are widely used in ambient temperature cured coatings and flooring applications. Theses products are also used more and more in cold temperature applications. (See Successful Cold Temperature Application on the Technology Update page). **If amine-cured epoxy resins polymerize during conditions of cool ambient temperatures or high humidity, i.e. condensation on the coating, they may develop an amine blush. **The amine at the coating surface develops as an oily, waxy or milky film, sometimes amber to clear in color.
The amine component reacts with moisture and atmospheric carbon dioxide to form ammonium bicarbonate and/or ammonium carbamate. This may or may not be visible on the coating’s
**surface but can interfere with adhesion if overcoated. **Contractors and inspectors should be alert to this phenomena and test suspect surfaces.
These amine compounds are often hygroscopic and very efficient scavengers of carbon dioxide from the air, even though carbon dioxide is generally present at about 360ppm in outdoor environments. In indoor environments with human activity this may be increased 2-3 times. In the presence of gas burning motors (fork lifts, tow motors) and salamanders etc., the carbon dioxide would be even greater. These sources of heat may also produce copious quantities of water vapor resulting is exacerbated blushing problems.
If amine blush is detected it should be removed.
hygroscopic – **absorbing moisture, **capable of easily absorbing moisture, e.g. from the air
Carbon dioxied is highly soluble in water (i.e. moisture).