Mahogany Side Table Resurfaced

Mahogany Side Table Resurfaced

Applying Fresh Veneers over Damaged Substrates


Published: 5/3/2015
By: Jerome Vernon
About the Author: Jerome Vernon is a software developer/project manager and an avid antiques enthusiast. When Jerome’s not busy creating business related software products for his clients he’s restoring antiques and writing articles for Restoration News.
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Mahogany Side Table Resurfaced (by Trial & Error)
Applying Fresh Veneers over Damaged Substrates

A while back I picked up this small table at an estate sale for next to nothing. The previous owner mentioned the hole on top was caused by a wet plant and over time the veneer had simply flaked away. Upon first glance I knew this table would make great subject matter for an article about resurfacing using wood veneers.

You may have noticed that a number of previous articles have mentioned resurfacing but without much detail about the process. This is the first in a series of articles that describe the process in detail. I have found that applying fresh veneers over a damaged surface is a viable way to completely revive the look of a once dilapidated piece.

During this demonstration, I’ll make a common mistake which will then be corrected thus providing the opportunity to view the results of various techniques.  As can be seen, the damage on this table penetrates completely through the decorative veneer, underlying cross-banding and to the bare-wood substrate. Water has also penetrated the joints of the substrate causing partial separation.

In this article, I will resurface the top and base of the table with ribbon striped (also known as ‘quarter cut’) African mahogany veneer. This paper-backed material is only 1/100th (10mils) in thickness. It’s relatively soft and easily cut using a sharp pair of upholstery shears. I will demonstrate several types of heat-activated adhesives and use a common household iron to adhere the veneer to the substrate. The table will then receive a beautiful mahogany finish with a satin lacquer topcoat.

Step 1 – Finish Removal and Surface Preparation

Prior to applying the new veneer, the table is completely disassembled. Next, the existing finish is removed using a solvent (acetone) washable methylene chloride solution. The individual components are then sanded, beginning with P120 and ending with P240 MIRKA® Abranet abrasives, using an interface pad with the MIRKA® DEROS random orbital sander. Contoured areas are sanded with the same grits using MIRKA® Goldflex Soft foam-back abrasives and, the inside crevasses cleaned using a sharp cabinet scraper.

During surface preparation, I will fill the large area of damage using Durham’s Rock-Hard Water Putty. This wood filler is self-leveling and fast curing.

Note: For veneer work, some professional recommend using automotive body filler such as BONDO® for patching of small areas. Instead, I will fill the defect with water-based putty and then sand to achieve a level surface. This ‘non-recommended’ method will demonstrate the results of applying thin veneer over an imperfect substrate.

The putty is packaged as a powder and is mixed with a small amount of water to form a high viscosity liquid. It is poured (slightly over-filled) into the void and allowed to cure for ~4 hours.  Once cured, this putty is quite hard and can be easily shaped using abrasives or sharp tools. Shown left, with the sander running at a moderate speed, the putty is sanded smooth with P120 and ending with P240 Abranet.

Step 2 – Cut, Apply and trim Veneer

Paper-backed veneers are typically available in 10mill or 20mil thicknesses. This thin 10mill veneer is easily cut to shape using upholstery shears. Here it is cut slightly over-sized (~1/16 inch) and will be further trimmed to a perfect fit after gluing.

Traditional hide glue is a popular choice for many applications in woodworking. Although now available in a liquid (ready-to-use) formulation, the granular form is often preferred. Granular hide glue is prepared by adding water and heating to a temperature of ~140 deg. F. For this project, I will apply the glue to both substrate and the paper-side of the veneer. After allowing the glue to cure, the veneer will be aligned onto the substrate. A household iron set to ~170 deg. F will be used to re-melt the glue and create a tight bond.

Note: When working with 20mill, cross-banded (2-Ply, wood-on-wood) or other thicker veneers, heat transfer is much less effective so alternate adhesives, such as contact cement or cold-press veneer glue is usually recommended.

To allow easy spreading, this hide glue mixture is prepared relatively thin by adding a little more water to the granules.  A thin film of glue is applied to both substrate and allowed to cure for several hours.

Although somewhat gummy the veneer is positioned onto the substrate. Prior to ironing, a light mist of water is be sprayed onto the veneer which relaxes the grain and aids heat transfer. While ironing, a veneer scraper is used to remove bubbles and to force excess glue from under the veneer. The rubbery excess glue (squeeze out) is peeled away and overhanging veneer trimmed flush using a small wood rasp and P120 sandpaper/block.

After resurfacing the table top and table base, all components are lightly sanded and the table is re-assembled, ready for finishing.

Step 3 – Finishing

This article is not specifically about finishing so I will cover this section in summary. 

Ribbon striped mahogany veneer is always quarter cut through the annual growth rings at a right angle producing a shimmer (chatoyance, or cat's eye effect). To accentuate the woods natural radiant effect, yellow dye stain is reduced in color strength by ~50% and is spray applied in two passes.

(Note: For this project, the Apollo Spray Systems 8200G ‘Super-Spray®’ true HVLP spray gun is used. This high performance spray gun has a 400cc side mounted adjustable gravity cup and provides superb atomization along with high HVLP efficiency.)

Next, a highly reduced coat of vinyl sealer is spray applied and allowed to cure for ~1 hour. The entire surface is then scuff sanded lightly using MIRKA® P320 Abranet, sanded just enough to remove any raised grain (fuzz).

Mahogany colored oil-based grain filler is mixed 50/50 with neutral grain filler to reduce its color contribution. Using a plastic spreader the grain filler is applied evenly to the entire surface. After the grain filler had settled for ~20 minutes, a MIRKA® ‘Mirlon Total’ ultra-fine scuff pad is used to compress the grain filler into the wood pours and to sweep away any excess material. The filler is allowed to fully cure (~24 hours) before spray applying a full (unreduced) coat of vinyl sealer effectively sandwiching the grain filler between sealer coats.  The sealer is allowed to cure for several hours then sanded fairly vigorously using MIRKA® P240 Abranet with the MIRKA® DEROS sander set at a modest speed.

Next, a dark mahogany glaze stain is applied liberally with a rag. To accentuate the ribbon pattern of the wood, a glazing/graining brush is used to create areas of highlights and shading. In the final step, three coats of Mohawk Finishing Products ‘Buffcote™’ satin (40 sheen) lacquer is spray applied.

All looks great when viewed at a right-angle under direct sunlight. However, when viewed at a slight-angle a noticeable surface imperfection is clearly visible. The imperfection is due to errors in the patching (putty) method as described in the first step of this article. It is nearly impossible to effectively repair deep/large areas by filling/leveling and overlaying with a thin (10 mil) veneer. When applying and curing, downward pressure and the adhesive will force the veneer to the contour of the substrate thus revealing any surface defects.  Any surface defects are further accentuated by a glossy topcoat.

Read on for the solution…

Step 4 – Applying Cross-Banded Veneer

When filling large voids, an epoxy based automotive body filler such as BONDO® is usually recommended over water-based fillers (Veneering: A Foundation Course by Mike Burton ISBN 978-1402726491). In addition, glazing/spot putty is used around the margins of the filled area to feather the repairs.  For wood patching applications, this approach is usually only effective for repairing smaller defects or for less noticeable areas of the piece.

A better approach for applying veneer over imperfect substrates is to utilize a thicker and more stable cross-banded veneer (commonly referred to as wood-on-wood or two-ply veneer). This can be done on-the-fly by applying two layers of veneer (10mil or 20mil) with the grain running perpendicular to each layer. For a modest extra charge two-ply veneer can be purchased directly from most veneer suppliers. Two-ply veneer is prepared by the supplier in a controlled process using a large/heavy press and bonded with specialized adhesives.

There are plenty of choices with respect to veneer adhesives. We have already discussed traditional hide glue. Other adhesives include veneer contact cement, cold press, heat lock, PSA and PVA glue. Although popular among woodworkers, PVA adhesives (white/yellow/brown carpenters glue) will soak into and seal the woods and are resistant to oil and solvent based coatings. The use of PVA adhesives is often discouraged for veneering applications. For this project, we will deviate slightly from step #1 and use Better Bond Heat-Lock™ adhesive which spreads on thin, easier, and has cross-linking polymers for a stronger bond.

For detailed information about veneer adhesives visit the Joe Woodworker website. Here is the link to an article written by Joe that explains the various adhesives along with application examples for each. On the Joe Woodworker website you will also find many other informative articles about veneering in addition to his on-line store where high quality veneers, tools and supplies are available.

Two sheets of 10mil veneer are cut and the old veneer/underlayment is sanded completely away from the substrate using MIRKA® P80 to P120 Abranet with the MIRKA® DEROS sander set to a high speed.

Using a glue roller, a thin but complete coat of Heat Lock adhesive is applied to the substrate and backs of each precut veneer sheet and allowed to cure for two hours. Prior to applying heat, to pre-soften veneers, a light mist of veneer softener was sprayed over the tops of the veneer sheets. Each veneer sheet, one at a time is positioned and pressed in place using a household iron preset to ~175 deg. F.

Next, the excess adhesive (squeeze-out) is removed with warm water and overhanging veneer trimmed flush using a rasp and P120 sandpaper/block.

The table top is then finished using the same schedule as described in step #3 and reattached to the pedestal. Notice that the resulting surface is now exceedingly level and appears perfect.

Conclusion

In this article, two different approaches to resurfacing using paper-backed 10mil wood veneer were demonstrated and the final approach proved more effective than the first. With antiques, wood-on-wood (two-ply) veneers are very common and when extensive damages to the decorative top and underlayment have occurred, the best results are obtained when both are replaced. For less dramatic damages to decorative wood veneers such as slight lifting, burn holes or corner chips, less invasive repairs methods a more appropriate.  Examples of such repairs may include patching, filling or injection of hide glue under the lifted surface using a syringe.

Within the examples described above, the veneers were applied with heat-activated adhesives using an ordinary household iron. This popular iron-on technique works well with thin (10mil) wood veneers however, for 20mil and two-ply veneers, heat transfer is much less effective so eventual adhesion failure is more likely. It is important to keep the iron in constant motion and, to avoid scotching/discoloration, the iron temperature should not exceeding 200 deg. F. For thicker veneers, other adhesives/techniques such as cold press or contact adhesive formulated for veneers are most often recommended.

I’m happy with the way this small table turned out. I’m also glad that I took the small amount of extra time necessary to correct the mistakes introduced in Step #1 of this article. This once dilapidated table has now found a new home where it proudly adorns a piece of fine pottery filled with water-free artificial foliage.


 


 
References
  
Joe Woodworker - Veneering articles and supplies
   Joe Woodworker Website
  
Veneering: A Foundation Course by Mike Burton ISBN 978-1402726491
   Click to visit Amazon's source
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