Fast vs slow size question?

[joe cieslowski]

"Slow size lasts the longest!"

Why? If the gold covers the size, doesn't it protect the size untill the gold is eroaded?
How/why does the slow size "last longer"?
And, what are we talkin here.....weeks, years or decades?

I've had this question on my mind (what's left of it) for a very long time.

Thank you in advance!

Joe,

Makin Chips and Havin Fun!

[Kent Smith]

Quick Size and Fast Size are varnishes based in resins that cure and harden over time. Even under gold, this type of resin will finish the process of hardening over a period of years, perhaps 5 to 10 to 20, even longer, depending upon ambient temperature and humidity. This process causes the resin to return to its original molecular state which means two things occur. The first is at the extreme, the resin turns to powder. You can see this on antique furniture which has not had an oil or wax treatment to rejuvinate the finish. The second unavoidable effect is that the varnish looses adhesion both to the surface and to the gold that is stuck to it. The latter is the most devastating for a gold leaf finish.

Slow size on the other hand is a fattened oil, usually a blend of oils with a small amount of curing agent. The best slow oil size will never actually cure, retaining its elasticity and adhesion quality forever. This is then the best option for really long term durability. Gilded domes are expected to last 40 to 50 years and typically only need regilding because the abraision of weather has gradually removed the gold.

The real question then becomes, what is the service expectation for the project at hand. We must select the size we use based upon the longevity expected from the finished project. This is much more important than choosing a size based upon the application expediency. The old rule was, use quick size only for those projects that were expected to last only 5 to 10 years, for instance trucks. Considering the changes in ingredients, ie no lead, I would say the expectation for the resin sizes has shortened perhaps by half or more. We won't know for certain how long the current formulations will last until they fail in real situaitons. This is not the type of application that an accelerated testing will reveal much helpful information. I tend to lean to the conservative side when choosing a size and have a lofty expectation that my work will last forever.

[joe cieslowski]

Now I finally know.

I switched to the fast size about 4 years ago and so far so good. (Purely for production reasons)

Thank you very much Kent......you are a treasure!

Joe,

Makin Chips and Havin Fun!

[Mike Jackson]

We've used quick size for almost everything since we moved here 22 years ago. I wouldn't hesitate to use it on anything that called for quick work. Our envionment has always been on the dusty side. The longer wet size was exposed to the dust, the more we found it in the final gild. Usually. the "window" was shorter for gilding quick size, so that had to be factored in. You simply have to be there at the right time, or miss it. Slow size is more forgiving in that respect.

From my experience, I'd say the big issue is how well the substrate is going to hold up, vs whether the gold will hold up on it during that time. MDO and plywood certainly has a useable lifespan. Cedar and redwood will, too. The HDU foams seem to be doing very well around here, along with the PVC signs we made.

It is interesting we are talking about 7 to 10 years, or longer. When the first high performance vinyls were coming out, they were rated at 5-7 years and experience shows they actually lasted a lot longer. Not only that, they held their color pigment very well. Our local transit system, owned by the town, is talking about the vehicle wraps and their expenses. Each bus wrap costs around $10,000 and have a life expectancy of around 2 years, maybe 3. I believe they were also talking about some sort of clear coating after that time to bring some colors back out.

Cheers,
Mike Jackson