ALTERNATIVES to varnish

[dmckruit]

The driers added are nothing special. Usually metal driers are added to help oxidize the resin to speed drying. The most common driers used are zirconium, cobalt, calcium and magnesium. Different driers help different stages of drying. Zirconium is used as a through drying agent and is usually used with cobalt, calcium or manganese that are top driers.

The top driers speed the dry of the top of the film coating, while the zirconium dries the coating between the substrate and the top of the coating. If you ever were able to put your thumbprint in a coated surface thats drying and the top is dry, put you can still see your thumbprint, then the inner portion of the coating is not dry yet. The zirconium takes care of this part.

If your coating has a pink or purplish cast to it, then you know there is cobalt in it.

At one time lead was a common drier, in addition to a component in a lot of pigments. The lead was banned in the 1970's, so now they use other metals in its place.

The PGME or Dowanol PM is a glycol ether cosolvent that is used to speed air dry and as a cosolvent to aid the water in dissolving efficiently in the resin. This also acts as flow agent and helps the coating stick to the surface of the substrate.

The n-metyl pyrollidine is an amine that raises the pH of the mixture so that the resin can accept the water. This is used in place of ammonia which evaporates out of the coating too quickly. This makes the coating more stable and increases the shelf life in the can.

The main thing that will dictate the performance of the coating is the resin, because the water, amine, and cosolvent will all go away upon drying.

[schaney]

Thanks for the additional info. Sounds like cobalt is the drier, it has a purplish tint when first applied.

[wannabefree]

Thanks, DM and others for the wealth of good info. I have given up my search for the perfect, no maintenance, goes on easy, dries fast, doesn't yellow, finish. I'm varnishing the interior though I would have been happier with lacquer because I can do multiple coats in a day. Unlike some, I'm not retired yet . I'll be using the EM9300 I bought on the exterior and will post with the happy (or unhappy) results in a few years, after I have a chance to see how it holds up. You just hate to make a mistake when you invest months and $k in something like this. Time will tell. The good news is that I have lost a pound a week since starting, 16 pounds now. I'll need to stretch this out for 32 more weeks. Maybe varnish isn't so bad .