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Slow Drying Glues

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I am looking for a glue to spray or brush on a screen (regular galvanized window screening) which will remain very sticky for at least 12 hours.

Can you help with a suggestion?

Thank You,

Barb

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You don’t mention whether your product is intended for interior or exterior use or what you want to adhere to the screen, so I will try to cover all the bases.

You will want to do some test patches to be sure you have the amount of tack you want; that you know how to recognize that point somewhere between wet and dry that is the tacky stage or “open window” when you can apply your artwork; and to make sure the finish looks acceptable and will stand up to its intended use.

Any glue’s drying characteristics can be depicted by a simple graph of a line sloping from the upper left to the lower right. The high point represents wet, the low point is dry and the horizontal axis is time.

Fast drying glues dry in a steeply sloped straight line fashion, that is to say, quickly.

The drying pattern for most paints and varnishes would be graphed with a flatter sloping straight line which spans a longer segment of the time line.

What you want is an adhesive which dries rapidly (starts as a steep slope) to a point where it is tacky; and then dries more gradually (slope flattens out a lot) giving you a sufficient open window to place the items you want to adhere. Sounds like a tall order, right?

Surprise! Those characteristics are exactly the design specs for “size”, which is the type of adhesive used for gilding.

Gilding is the art of applying very thin sheets (leaves) of gold or other metal to any paintable surface. It is also known as gold leafing. There’s no reason why size can’t be used to adhere other light weight media as well.

Size can be applied with either brush or spray gun. Package instructions tell you how long the size takes to “come to tack” or be ready to leaf, as well as how long the open window is. Note that cold or wet conditions will prolong both the come to tack and the open window time.

There are slow and quick dry sizes. Here are the pros and cons.

Quick Dry Size

• Pro – quick to tack
• Con – shorter open window
• Con – not self-leveling, so brush strokes will show through very thin media

Slow Dry Size

• Pro – long open window
• Pro – self-leveling
• Con – slow to tack

Unless otherwise noted, the sizes below are clear. An even coat of size is essential in gilding, so gilders frequently tint the size with universal tints which come in a range of colors and are compatible with oil, water and lacquer based paints. Being essentially wet pigments they don’t contain driers or retardants and will not affect the time to tack or open window. You can safely add up to 10% of tint.

A small amount of color allows you to see where you’ve been, as well as to provide glow or contrast where the leaf shows through. Tint used to assure an even coat should be in contrast to the background for best visibility.

Size for Exterior Use

LeFranc Mixton Oil Slow Size

LeFranc is the choice of professional gilders for their most important projects because of its consistency in time to tack and its long open window to leaf. It is sold in the U.S. but due to environmental restrictions, cannot be made here.

Initial tack time of Slow Size is about 12 hours and it has a safe open time of two weeks. However you don’t have to wait a full two weeks before finishing. It can be clear coated (if desired) and used after about 20 hours.

LeFranc Mixton Oil Fast Dry Size

LeFranc also produces Fast Dry Size which has a three hour time to tack and up to eight hours of open window.

Rolco Slow Set Size
Rolco is the leading U.S. brand of leafing size. The Slow Dry Oil comes to tack in six to eight hours and has an open window of the same duration.

Rolco Quick Dry Gilding Size
Quick Dry will reach tack in one and a half hours and have an open window of the same duration.

Sizing for Interior Use

Wunda Size

Wunda Size is a water based synthetic size for use on all interior gilding projects. It reaches tack in 15 minutes and has an open time for gilding of up to 36 hours. It is unparalleled for tack aggressiveness when using heavier media such as brass, copper or aluminum leaves. It is milky when applied and is ready to leaf when it turns clear. The milky appearance makes it easy to gauge coverage.

Rolco Aquasize

Rolco Aquasize a water-based size, is designed for all interior leaf work where an extended tack time is required. Proper tack will develop in 25 minutes and will remain open for gilding up to 36 hours.

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