On choosing the best gold leaf for various gilding situations.
The Best Gold Leaf: A Gilder’s Guide
When one says “best gold leaf,” it’s not quite as simple as picking the purest gold and calling it a day. Different project contexts—exterior surfaces, interior frames, glass (eglomise), decorative objects—demand different combinations of purity (karat), thickness, support format (loose vs transfer), and adhesives (mordants or size). What works best in each situation with logic behind the various karat options (24k, 23.75k, 23k, 22k, 18k, etc.).
SeppLeaf offers a broad line of genuine gold leaf in loose, patent, ribbon, etc. (SeppLeaf) Also, general gilding references, color/alloy discussion, and durability factors are drawn from established sources. (gildedplanet.com)
Core Principles & Terminology
Before diving into “what to choose where,” it helps to have some grounding in key gilding principles.
Gold Leaf Basics
- Gold leaf is beaten gold (or gold + alloy) so thin it becomes essentially translucent and mechanically fragile. (en.wikipedia.org)
- Because it is so thin, the underlying support (adhesive, substrate, bole, primer) significantly affects the final appearance.
- “Genuine gold leaf” is distinguished from imitation leaf (also called composition leaf, Dutch leaf, Schlämmgold, etc.) which contains no real gold but various base metals (commonly brass, copper, zinc). Imitation leaf will tarnish and must be sealed robustly.
- Leaf formats:
- Loose leaf (or surface leaf): pure leaf squares, usually interleaved between tissue papers.
- Patent / transfer leaf (aka “tissue-backed leaf”): leaf pressed onto a backing tissue so it can be handled more robustly, especially outdoors. SeppLeaf describes these “patent leaf / transfer leaf” forms and notes their common use in exterior gilding but also their limitations with highly detailed surfaces. (SeppLeaf)
- Ribbon leaf: leaf rolled on paper with slight overlaps; useful for covering large flat surfaces with an oil size and flat geometry. (SeppLeaf)
- Gilding in powdered form / shell gold / flakes: useful for small repairs, curved surfaces, or decorative touches. (en.wikipedia.org)
Thickness / Weight
Leaf thickness is often specified in grams per 1,000 leaves (or similar metrics). Heavier leaf (more grams per thousand) is marginally more durable to abrasion, wind, etc. (gildedplanet.com) For exterior applications, one might choose a slightly heavier leaf (within a purity constraint) to give extra “grit resistance.”
Karat / Alloy Choices: Color, Durability & Cost
Here’s a summary of how karat (purity) and alloy content matter in practice:
- 24k: Essentially pure gold (≥ 99.9% gold). Very yellow, and highly stable (non-tarnishing). But pure gold is softer, so very thin leaf can sometimes be more delicate to handle.
- 23.75k / 23.5k / 23k: These slightly lower purities introduce very small amounts of alloy (silver, copper, etc.) mainly to improve working characteristics and color balance. Many gilders treat ~23.5k or 23.75k as a “sweet spot” for combining durability and radiant yellow. For architectural / outdoor gilding, 23.75k is a commonly recommended high-end choice. (SeppLeaf)
- 22k: ~91–92% gold. Some color difference begins to appear; the leaf might be a bit less “rich” than higher karats, but is still fully genuine. Often used in interiors, frames, etc.
- 18k: 75% gold. More alloy (copper, sometimes silver), thus more color shifts (warmer tones, more reddish or “moon gold” variants). Less expensive. Used mostly interior or decorative where absolute top-tier color and stability are not demanded. (gildedplanet.com)
- Lower karats (e.g. 16k, 12k, etc.): More alloy, more color shift, and more risk of oxidation or reaction—thus usually reserved for decorative or accent work, not serious gilding surfaces.
In sum: as karat goes down, color shifts (toward red, pale, or less intense yellow), cost goes down, and stability (especially outdoors) declines. Many exterior specialists avoid using leaf below ~23k, unless the expectation is a limited lifespan or they are sealing heavily.
Choosing the Best Gold Leaf by Application
Now let’s go through the major gilding contexts, assessing what purity, leaf format, adhesives, and practical tips are ideal.
Exterior Gilding (Architecture, Domes, Statues, Outdoor Surfaces)
Recommended Leaf Purity & Format
- Use high purity: 23.75k is often considered top-tier for exterior use (balancing color, stability, cost) (SeppLeaf)
- 24k is also possible—but because it is softer and completely pure, thin leaf may be a bit more delicate to handle on large surfaces. Still, pure gold is chemically the most resistant to corrosion.
- Avoid lower karats (below ~23k) for exterior—it increases risk of corrosion or discoloration over time. (gildedplanet.com)
- Use patent / transfer leaf or ribbon leaf formats (tissue-backed or rolled) for large flat surfaces because these formats are easier to handle in wind, reduce waste, and reduce risk of tearing loose leaf. SeppLeaf explicitly notes that patent leaf is often used outdoors. (SeppLeaf)
Size / Adhesive (Mordant / Oil Size)
- Exterior gilding typically uses an oil-based size / adhesive (often called “oil size” or “mordant”) rather than water-based. The oil size must cure well and resist moisture.
- Use a slow-set or long open-time oil size if you have large areas to gild or complex geometry; or a quick-dry oil size for smaller surfaces or tighter working schedule. GildedPlanet describes variations in quick-dry vs slow-set oil size. (gildedplanet.com)
- Ensure full curing (often 24 hours or more, sometimes longer) before applying protective sealers or exposing to the elements. (gildedplanet.com)
Durability & Protection
- Even with genuine high-karat leaf, applying a protective clear coat (UV-resistant, breathable) helps shield the leaf from abrasion, pollutants, acid rain, bird droppings, etc.
- Leaf thickness matters: heavier leaf (higher grams per 1,000 leaves) gives better resistance to abrasion. Choose more robust leaf when possible. (gildedplanet.com)
- Maintenance: periodic inspections, gentle cleaning (not abrasive), and touch-ups may be necessary over decades.
Special Considerations
- If the substrate (wood, metal, stone) moves or flexes, the adhesive must accommodate slight movement without cracking the leaf.
- Edges, seams, corners are vulnerable; plan the leaf layout accordingly to avoid gaps or flaps.
In short: For exterior gilding, your “best gold leaf” will generally be 23.75k (or 24k if desired), in a transfer or ribbon format, applied with a robust oil-based size, cured and protected.
Interior Gilding (Picture Frames, Wall Trim, Mouldings)
Leaf Purity & Format
- You have more leeway indoors. Many gilders use 23k, 22k, or even 18k for indoor decorative surfaces.
- Loose leaf (surface leaf) is preferred for intricately carved frames, mouldings, and profiles, because it can be worked into recesses, corners, tooling, etc.
- Patent leaf may still be used for flat, simpler surfaces, but you lose some flexibility.
Adhesive / Technique
- Water gilding (using gesso and bole and a water size) is considered the “gold standard” for interior decorative gilding because it allows burnishing (with agate stones) to a high shine, and very fine, seamless leaf joins. It is demanding and time-consuming, but ideal for high-end interior surfaces. (en.wikipedia.org)
- Alternatively, oil size can be used indoors, particularly for furniture or surfaces not suitable for water gilding.
Protection
- Interiors generally pose fewer challenges, but use light varnishes or sealers to protect against handling, dust, cleaning solvents, etc.
Karat Strategy
- If you want maximum brilliance and resistance to tarnish, go toward 23k–24k.
- For warmer tones or cost savings, 22k or 18k can offer beautiful results—be aware they may darken slightly or shift over time, particularly lower karats.
- Some professionals prefer 23.5k as a standard compromise for many indoor decorative jobs.
Gilding Glass / Eglomisé (Back-side / Reverse Gilding on Glass)
“Eglomisé” refers to gilding on the reverse side of glass (or combining gold leaf with backing paint), so that the gold is viewed through the glass. Because the gold is protected behind the glass, many constraints of durability are relaxed, but other challenges emerge (adhesion through translucent layers, color halo, adhesion between gold and paint backing, etc.).
Leaf Purity & Format
- You can safely use high-purity leaf (23.75k or 24k) because the environment is protected by glass.
- Loose leaf is fine, because you can place leaf against the glass and press it. But transfer leaf can also be used (if careful) to reduce risk of tearing.
- Ribbon is rarely helpful here; the geometry is often flat but the need for precision is high.
Adhesive / Backing / Process
- A specialized reverse (back-gilding) adhesive or “reverse size” is typically used.
- The usual process is:
- Prepare the glass by cleaning thoroughly, then apply a size (adhesive) to the back (the side not viewed).
- Once tacky, apply the gold leaf onto the back, pressing it down.
- Cover the leaf with a protective paint backing (often black or colored lacquer) to hide the adhesive and provide contrast.
- Optionally, sometimes additional paint or effects are applied behind the gold to create patterns or shadowing, or you can lightly abrade gold to reveal painted areas (scratching or scraping, known as stippling, etching, etc.).
- Because the leaf is behind glass, you don’t need to worry about abrasion or weathering, but you do need perfect adhesion (no bubbles, no delamination) and the backing paint must bond well without chemical reactions interfering with gold.
Color & Aesthetic
- The purity of gold matters less for corrosion resistance since it’s sealed behind glass—but you still want a rich and stable tone, so 23k–24k is often chosen.
- Beware of “ghosting” or color shift: the interface between glass, adhesive, and gold can affect perceived color and brightness. Using a well-matched adhesive and backing is important.
Gilding Picture Frames & Moulded Objects
Picture frames provide many of the challenges typical to interior gilding: relief, corners, carving, tooling, joins, edges, etc.
Leaf Purity & Format
- Loose leaf (surface leaf) is almost always preferred for frames, especially detailed ones. It can be manipulated, cut, slipped, overlaid, tucked into corners.
- For plain flat surfaces (frame flatlands), patent leaf might speed things up, but risk of gaps or edge issues increases.
- Purity: 23k or 23.5k is often a go-to for frames; 22k or 18k can be used depending on budget/textural goals.
Technique
- Water gilding (gesso + bole + water size) remains the professional standard for high-end frames, allowing burnishing, seamlessness, fine joins, and optical purity.
- Oil size can suffice for less demanding work or for faster production.
- After leafing and burnishing, use fine varnishes to protect the surface from rubbing and wear.
Join & Corner Treatment
- On frame corners and tooling edges, plan leaf layout (start from centers, overlap, slip leaves, etc.).
- For frame edges, one may overlap slightly or “miter” the leaf edges so seams disappear.
Small Decorative Objects (Eggshells, Trinkets, Sculptures)
When gilding small objects—curved surfaces, irregular shapes, even delicate ones like eggshell fragments—the challenges are more about handling, fit, adhesion, and appearance than massive durability.
Leaf Purity & Format
- Loose leaf or shell gold / powdered gold is often best for flexibility and precision. For extremely curved, irregular, or tiny surfaces, shell gold (gold pigment made from ground leaf in binding medium) allows painting rather than applying full leaf. (en.wikipedia.org)
- Purity: You can use high purity (23.75k, 23k, or 24k) because environmental stressors are minimal. For pieces that may be handled, 23k–24k helps prevent oxidation and discoloration.
- If cost is a concern and the object is purely decorative (not handled), you might even use a lower karat leaf—but understand it may darken over time unless sealed.
Adhesive / Method
- Use a delicate water or alcohol-based size (for interior use) that can adhere cleanly, without causing pooling or delamination.
- For very small curves, you might “pre-bend” leaf, slip it, or break leaf into smaller pieces.
- Shell gold (as a brushable gold paint) is ideal for highlights or extremely curved surfaces where flat leaf would not conform.
Finishing
- Use clear varnishes or sealers suitable to the object’s intended use (e.g. low-VOC varnish, UV-resistant, non-yellowing).
- For fragile decorative items, a final micro-clear coat helps protect from fingerprints, dust, humidity, etc.
Karat Comparison Table & Practical Guidelines
Here’s a quick comparative summary of karat choices and their best use contexts:
| Karat (Purity) | Approx Gold % / Alloy | Color Tendency | Strength / Durability | Cost Relative | Best Use Contexts |
|---|---|---|---|---|---|
| 24k | ~99.9 % | Brightest yellow | Excellent corrosion resistance; soft | High | Exterior architectural detail (if skill allows), interior high-end decorative pieces, background leaf behind glass, small decorative works |
| 23.75k / 23.5k | ~98–99 % | Vivid, warm yellow | Very good durability; slight alloy improves handling | Slightly less than 24k | Exterior surfaces, large architectural gilding, interior frame work where long life is desired |
| 23k | ~95+ % | Slightly warmer or “redder” yellow | Good durability | Moderate | Interiors, decorative surfaces, furniture, frames |
| 22k | ~91–92 % | Slightly softer yellow | Good but slightly less resilient | Moderate–lower | Interior decorative surfaces, frames, accents |
| 18k | ~75 % | Warmer, slightly reddish / “moon gold” tones | Lower corrosion resistance; more color shift | Lower | Decorative trims, accent areas, decorative objects (indoor) |
| 16k / 12k | ~66.7 % / 50 % | Paler or more alloyed colors | Much lower corrosion resistance; more reactive | Low | Very decorative work, indoor use only, accent or contrast, not structural gilding |
Practical rules of thumb:
- For any exterior or semi-exposed work, aim for ≥ 23k purity (preferably ~23.75k or 24k).
- For interior high-end decorative work, 23–24k gives superior color, but 22k or 18k may be acceptable depending on budget and aesthetic goals.
- For small or decorative objects not subject to heavy wear, the purity requirement is relaxed; focus more on handling and finish.
- Always seal or protect the gold leaf when possible to prolong life, especially in lower karats.
Why the Many Intermediate Karats (23.75, 23.5, 23, etc.) Exist
You might wonder: why not simply make only 24k leaf and call it a day? The existence of many intermediate karats (23.75, 23.5, etc.) is a result of balancing workability, color tone, and cost.
- Pure gold (24k) is soft. At extreme thinness, it can be more prone to damage, tearing, or minute defects. Slight alloying can improve handling without materially sacrificing corrosion resistance.
- The tiniest alloy shift (e.g., 0.25k of silver or copper) can subtly adjust hue, allowing manufacturers to fine-tune the warmth, brightness, or contrast of the leaf to suit aesthetic preferences or match periods.
- Because gold is expensive, reducing a tiny fraction of gold content (e.g. from 24k to 23.75k) yields cost saving while maintaining almost identical optical and durability performance in practice.
- Over time, some alloyed leaf (especially lower karats) may exhibit slight oxidation of the alloy metals. So the lower the karat, the more likely you’ll see color drift over decades if not well protected.
In practice, 23.75k or 23.5k is often chosen as a nearly “sweet spot” for combining color richness, workability, and long-term stability—especially in architectural or exterior gilding roles.
Practical Advice & Pitfalls (From the Field)
- Test on a sample: Always gild a small hidden piece first (especially when combining a new leaf, adhesive, or substrate) to check adhesion, tone, and finish.
- Humidity & handling: Gold leaf is extremely delicate. Drafts, static, humidity changes, or mishandling can cause tearing or wrinkling. Use humidity control and gentle techniques (gilder’s tip brush, etc.).
- Leaf joins: Plan how leaves overlap or butt, especially on large surfaces. Poor joins will show seams.
- Sealers carefully: Some varnishes or coatings may interact with the leaf or adhesive; always test small patches.
- Cleaning / maintenance: Use very gentle cleaning (soft cloth, mild solvent, no abrasives). For outdoor gilding, periodic inspections matter.
- Edge protection: Corners, seams, edges are vulnerable. Consider beveling or overlapping leaf strategically to avoid flapping.
- Expect some wear: Even with perfect application, some deterioration may occur over decades, so plan for touch-up or re-gilding.
- Cost planning: High-purity gold leaf is expensive; factor the waste (leaf torn or misapplied) and budget buffer.
- Supplier and pedigree: Use reputable suppliers (e.g. SeppLeaf, Manetti, Brambilla, etc.) to ensure consistency, authentic purity, and reliable backing tissues. SeppLeaf offers a wide array of genuine gold leaf products (loose, patent, ribbon) across many karats. (SeppLeaf)
Conclusion
There is no single “best gold leaf” in absolute terms. Rather, the best choice depends on where you’re gilding (exterior, interior, glass, small objects), what look you want, and how long you want it to last. For exterior gilding, high-purity 23.75k (or 24k) in transfer/ribbon format with a robust oil size is often the top choice. For interior and decorative work, 23k, 22k, or even 18k can be viable, especially when paired with careful technique (water gilding, burnishing). For glass or small objects, purity is less of a structural concern, so flexibility, handling, and finish often drive the decision.
