Test 7

Serious appraisers rarely rely on a single clue. They run a consistent battery of small examinations—quick, non-destructive checks that build toward a defendable opinion. Think of it as a 7-test method you can apply in the field before deciding whether to buy, consign, or escalate to a specialist. Below, we break down those seven tests, the tools that make them easy, and the telltale signs that separate genuine age from manufactured “oldness.”

The 7-test method: your structured first pass

1. Materials and construction

• Furniture: Identify wood species and how parts were joined. Hand-cut dovetails (irregular, with tool chatter) point to pre-1860 work; machine dovetails (uniform pins) appear later. Pit-sawn boards show straight, slightly irregular kerfs; circular saw arcs signal mid-19th century onward. Hand-wrought nails are pre-1800, machine-cut nails are c. 1800–1890, and round wire nails dominate after the 1890s. Early screws have off-center, shallow slots and irregular threads.
• Paintings: Linen vs cotton canvas, hand-made vs machine-woven canvas, glue/chalk grounds vs modern acrylic gesso. Panel paintings should show seasonal movement; a perfectly flat “old” panel with no shrinkage or checks is suspect.
• Ceramics and glass: Examine paste and glaze. Porcelain translucency, footrim wear, and, for glass, pontil scars and mold seams tell production method and period.
• Metals: Bronze should show crisp chased details and cold-worked finishing; spelter (zinc alloy) often looks softer, with blunt detail and brittle breaks.

2. Tool marks and technique

• Wood: Gouge tracks, plane chatter, and hammer-set nails suggest handmade work; router chatter, uniform saw kerfs, and staples indicate later mass production.
• Metal: Filing and chasing marks in recesses indicate hand finishing after casting; heavy seam lines with minimal cleanup suggest lower-quality sand castings.
• Works on paper and prints: Under magnification, intaglio prints show plate impressions and ink sitting in incised lines; lithographs show grainy crayon textures; photomechanical halftones show regular dot patterns. If a “19th-century etching” is built of uniform CMYK dots, it’s a reproduction.

3. Signatures, marks, and provenance anchors

• Signatures: Genuine signatures integrate with surface aging—over, under, or within varnish appropriately. A bright, glossy signature floating on a dull, older varnish is a warning.
• Hallmarks and factory marks: Understand ranges rather than absolutes. Sterling marks, assay hallmarks, foundry stamps, registration numbers, and guild marks can date a piece, but they are also forged. Confirm mark placement, font, and spacing against known period practices.
• Labels and inscriptions: Gallery labels, exhibition tags, inventory numbers, and shipping labels often supply a timeline. Check for “shadowing” or oxidation halos under removed labels—evidence of long-term placement.

4. Condition and restoration

• Paintings: Under UV, natural resins typically fluoresce greenish; many modern retouches appear dark patches. Relining, overpaint, and varnish disturbances alter value and attribution risk.
• Furniture: Look for replaced feet, drawer runners, and hardware. New screws in old holes, fresh wood exposed by re-gluing, and mismatched oxidation indicate interventions.
• Ceramics and glass: Hairline cracks reflect light differently; restoration fills are smoother and may fluoresce under UV. Crazing should be proportional to age and use, not uniformly “painted on.”

5. Measurements and proportions

• Dimensions: Verify claimed sizes. Period frames often vary from modern standard sizes; “perfect fit” modern canvases in “18th-century” frames deserve scrutiny.
• Weight and feel: Bronze is heavy for size and rings when lightly tapped; spelter is lighter and dull. Glass thickness and foot balance reveal quality. Calipers and a small scale detect inconsistencies.
• Proportion logic: Period makers followed consistent design logic; anachronistic proportions or mismatched moldings can betray composite pieces.

6. Dating via component science

• Pigments: Titanium white becomes common in the 20th century; phthalocyanine blues/greens after the 1930s; Prussian blue appears after 1704; zinc white becomes widespread in the 19th century. A “17th-century” canvas with modern pigments is a contradiction.
• Supports and glues: Animal hide glue predominates in pre-20th-century furniture; synthetic PVA and epoxy point to later repairs. Canvas tacks vs staples help date stretching.
• Scientific methods (when needed): XRF can screen metal alloys and paint pigments non-destructively; TL (thermoluminescence) is used for low-fired ceramics and terracotta; dendrochronology can date wood panels when species and sapwood are present. Use these to confirm, not to “make” authenticity.

7. Market comparables and value context

• Comparables: Match maker, period, size, subject, medium, condition, and sale venue. Adjust for premiums like sought-after subjects and proven exhibition history.
• Value types: Distinguish fair market value (arm’s-length sale) from retail replacement (insurance). Not all “record prices” transfer to private sales.
• Risk discounts: Works with uncertain attribution, heavy restoration, or incomplete provenance trade at a discount. Factor authentication and legal risks into valuation.

Field toolkit and quick techniques

A compact, well-chosen kit can elevate your on-site judgment without risking damage.

• 10x triplet loupe: For tool marks, craquelure, fibers, and print screening.
• 365 nm UV torch: To assess varnish and retouch; use in a dim room and shield stray light.
• Strong LED flashlight: For raking light to reveal surface topography, overpaint ridges, and substrate joins.
• Pocket magnet: To detect iron armatures, steel screws behind bronze, and hidden reinforcements. Do not use it to distinguish bronze from spelter; both are typically non-magnetic.
• Soft measuring tape and calipers: For exact dimensions and thickness.
• Portable scale: Weight provides clues for metal composition and quality.
• Microfiber cloth, nitrile or cotton gloves, and a clean, dark cloth backdrop: For safe handling and better visual contrast.
• Notebook or app with a standardized condition template: Consistency beats memory.
• Dental mirror: To inspect undersides and tight recesses without disassembly.

Technique tips:

• Raking light: Hold the flashlight nearly parallel to the surface. Craquelure, raised retouch, and panel joins pop into view.
• Back-of-work inspection: The reverse of frames, canvases, and panels often holds the most honest information—oxidation, labels, stamps, and uncleaned surfaces.
• Corroborate clues: One anachronism may be a repair; multiple conflicts usually mean the story is wrong.

Reading genuine age versus fake patina

Artificial aging is improving, but real wear still follows logic.

• Wear patterns: Use follows the hand. Drawer pulls polish at contact points and dull within recesses; chair stretchers wear on foot-contact sides; gilding rubs on protrusions, not in crevices.
• Oxidation gradients: Hardware removed after long periods leaves a “shadow” where oxygen was excluded. Uniformly bright wood under widely replaced handles suggests recent changes.
• Wormholes: Genuine worm tracks are tapered, irregular, and penetrate at varied angles, often with exit holes; drilled fakes are clean, perpendicular, and oddly uniform. Check for worm frass (powder) in hidden cavities.
• Shrinkage and movement: Panels shrink across the grain, not with it. Miters open differently on old frames than on newly distressed ones. Veneer cracks should mirror substrate movement, not appear randomly painted.
• Varnish and surface: Period varnishes yellow and crack with time; modern glossy “brown” stains slapped over new wood to suggest age often pool unnaturally in recesses.

Documentation, comparables, and value

After the physical review, put the story in order.

• Condition report: Capture front-and-back photos, raking light shots, and UV views. Record all inscriptions, labels, marks, joins, and alterations. Note measurements and any instability (loose joints, tenting paint).
• Provenance chain: List owners, dates, dealers, auctions, exhibitions, and publications. Seek continuity; large gaps or sudden leaps to prestigious names require proof.
• Comparable sales: Choose comps that match closely on maker, medium, size, subject, and period. Adjust transparently for condition and restoration, and note the sale context (high-profile evening sale vs regional day sale).

When to escalate to labs and experts

Know the limits of fieldwork. Some questions require lab data and specialist opinion.

• Red flags for scientific testing:
  • Claimed high-value attribution with weak documentation.
  • Materials/pigments inconsistent with the stated date.
  • Suspiciously uniform craquelure or improbable condition.
  • Bronze with uncertain alloy and casting method.
  • “Archaeological” ceramics without excavation history.
• Methods to consider:
  • XRF for elemental analysis of metals and pigments.
  • FTIR or Raman for binders and varnishes.
  • TL for low-fired ceramics and terracotta.
  • Dendrochronology for oak and other suitable panel woods.
• Legal and ethical context:
  • Be mindful of cultural property laws, restitution issues, and endangered materials (ivory, tortoiseshell, certain woods). Marketability can be affected by restrictions even when ownership is lawful.

Practical checklist: a 7-step on-site appraisal

• Establish a neutral workspace with good light and a dark cloth backdrop.
• Record baseline data: measurements, medium, and overall photos (front/back).
• Materials and construction: check joinery, tool marks, supports, and hardware.
• Surface analysis: raking light for craquelure, overpaint ridges, and joins; UV scan for varnish and retouch mapping.
• Marks and documentation: examine signatures, stamps, labels, inscriptions; photograph and transcribe.
• Consistency check: reconcile materials, technique, and marks with claimed date and maker; list any anachronisms.
• Market context: identify three close comparables and note differences; flag authenticity or legal concerns that would affect value. Decide whether to walk away, negotiate, or escalate to specialists.

FAQ

Q: Is a UV flashlight safe for artworks? A: Used briefly and at an appropriate distance, a handheld 365 nm UV torch is non-destructive. Avoid prolonged exposure, don’t heat the surface with your lamp, and never use cleaning agents under UV during inspection.

Q: Can a magnet tell me if a bronze is genuine? A: No. Bronze and spelter are both typically non-magnetic. A magnet can reveal hidden iron armatures or steel screws, but alloy identification requires weight, visual analysis of casting quality, and, if needed, XRF.

Q: Should I clean an object before appraisal? A: No. Surface residues, oxidized varnish, and dirt patterns provide critical evidence. Cleaning can remove information and reduce value. Document first; if conservation is indicated, seek a professional conservator.

Q: How reliable are hallmarks and signatures? A: They are helpful, but both are forged. Confirm placement, font, and period consistency, and corroborate with materials, technique, and provenance. Treat signatures and marks as one data point, not final proof.

Q: What’s the difference between authentication and appraisal? A: Authentication addresses authorship and date; appraisal assigns value for a defined purpose (sale, insurance, donation). Appraisals depend on authenticity; when authorship is uncertain, value reflects that risk.

Apply the Test 7 approach consistently—materials, technique, marks, condition, measurements, components, and market—and you’ll reduce costly mistakes, communicate clearly with clients, and know exactly when to call in deeper science or a specialist opinion.