Crib – Finishing and Assembly

Finish, then Assemble design

This design is based on the technique of: finish, then assemble. This will sound backwards to most people, but is a very logical and efficient way to do certain kinds of projects – especially those with lots of small parts.  It works well with many Craftsman designs or adaptations of them.

The primary key to making this succeed is to have joints where every surface has a reveal or offset.  This begs for mortise and tenon joinery as well as flat recessed or raised panels. This project was designed for reveals and recessed flat panels.

When designing a piece for this technique it is easy to go overboard with large reveals. This has 1/16″ to 1/8″ reveals. The key point is to not have any adjacent surfaces that when assembled must be flush (and then require sanding, planing or scraping).

The beauty of this technique is that the surface preparation is easy.  I really hate sanding and scraping into corners and to do this between spindles is a special kind of hell. It is so easy to create a divot while attempting to clean up that last little bit of “something”.  With the  all flat surfaces and you can spray the finish on all horizontal pieces ( no runs).  This works well if you don’t spray finish on a daily weekly or even monthly basis.

Sanding and scraping

I sand all of the pieces to 120 grit and definitely hand sand or scrape again after the drum sander to avoid nasty longitudinal scratches.   With well figured wood I will then hand scrape as well to better “pop” the figure once finish is employed.    Note that scraping after sanding requires more sharpening but this is a small price to pay.  For any large flat surface, scraping really is a must. It is not only faster than a good sanding job but also gives a better more transparent finish in the end (more chatoyance).  The random orbit sander no longer has a place here, as I am tired of cleaning up swirliques that show up once the stain is applied.

Spraying

Once the parts are sanded I lay them out on left over strips of wood for efficient spraying. The goal is to have them close enough to minimize wasted finish but far enough apart to get good edge coverage.  When gang spraying pieces like this  I spray at approximately a 30 degree angle so that the edges get good coverage. The rack of pieces gets 2 passes so that I can hit both sides. This means that as you walk down the row the first pass will not have full coverage on the face, but as you reverse direction for the second pass it will.  The edges achieve full coverage as the get hit when each face is sprayed.

When I first started doing spindles like this, I placed them close together and sprayed per normal directions and still had uneven sides. Using the current technique the sides turn out great and it only takes half the time as I only flip once per coat instead of four times .

Mortises and dadoes when finishing

For proper glue adhesion, you really do not want to have the finish layers inside of the joints.  Having finish inside of the joints is a recipe for glue bond failure.  The tenons are easy – tape them.

However the mortises and dadoes are more difficult. There are two major types: those that meet with a shoulder and those that do not. The top and bottom rails are good examples of those that meet with a shoulder. The mortise is hidden well within the end of the stock with the tenon that fits into it. These well hidden mortises can be covered with masking tape. The mortises and dadoes that will not have broad shoulders covering their edges are more difficult as masking tape will easily protrude on to what will be exposed areas.  Rolled up paper towels , newspaper and even wooden scraps can work, but the easiest by far is using foam “backer rod” that is used for weatherstripping and to fill the big gaps in your house that you can then caulk over.   Here we have 1/2″ backer rod filling some of the mortises.  The pieces can easily be re-used for future projects.

 

Finish schedule – all sprayed except for the gel stain:

Behlen solarlux dye – Golden fruitwood

2 light coats 1 lb cut garnet shellac

General FInishes gel stain – mix of 2 parts Georgian Cherry, 1 part Candle lite   – rub on, rub off and let dry 5-7 days. The long dry time is due to it  (oil based stain) being followed up with a water based finish

1 coat General Finishes Endurovar gloss precat water based urethane

2 coats General Finishes Endurovar Satin precat water based urethane . The precatelyzed polyurethane is exceptionally durable and UV resistant.  It is very brushable as well . I also enjoy the opportunity to promote a local business which really does have a superior product.  Their factory is <20 miles from my home.

If you are wondering; “Why gloss then satin?”. The reason is that the first coat of finish is often much heavier than the later ones,  and each coat of satin will drop the clarity of the finish. So the rationale is to build up the finish coats with gloss for depth and  sandability. Then switch to satin for the last 2 coats to provide the desired lustre.  While I would prefer to have just one coat of satin for best clarity, my technique is imperfect and I need 2 coats of satin to make sure there are not glossy patches showing through in the final finish.   I do the same with most other finishes where I want a non-gloss lustre.  The exception is Sherwin Williams pre cat rubbed effect lacquer.  This stuff is glorious, but must be used outside due to toxicity and not wanting to risk the house going BOOM.

Final assembly

Once the pieces have been finished, it is time for assembly.  This is where the epoxy comes in. This is not just the fast hardening hardware store syringes but rather the slower setting high strength epoxies from: Gougeon Brothers / West System, System 3 and Glen-L Marine Designs.  Beware of those selling “penetrating epoxies” which are basically the same base components with thinners / diluants but then lack in mechanical strength.

For the final assembly we do one last dry fit-up.  This verifies that we have all of the right pieces in place and there are no finish issues (blobs) impeding assembly.

The epoxy is thickened with silica. The colloidal silica keeps it from running or sagging during assembly. The high strength silica adds bulk. Think of adding sand and stone aggregate to concrete as the logical equivalents.   This mix is then tinted to match the darker colors in the wood.  The dark colors blend in well to the grain and look natural in the crevices of the joints if your clean up is imperfect. However if it is lighter than the background wood color it will stick out like a sore thumb.

We are also careful to clean up any squeeze out or fingerprints with plenty of paper towels and denatured alcohol. The epoxy will discolor in sunlight due to the UV rays and what may not be noticeable now may very well be in 5-10 years.