I have laminated a mahogany handrail, and I need to fill seams that exist in some areas between the laminations. Based on the responses to a previous post, I had planned to use a combination of fine mahogany sawdust and hide glue. I mixed a small batch and tested it on an extra section of handrail. Unfortunately the hide glue made the sawdust darker than the surrounding wood. Since the handrail will be finished with a very light stain or just a clear finish, I need the filler to match the wood color as closely as possible. I have attached a picture of my hide glue filler test. The left side of the picture shows the area that was filled with the hide glue / sawdust combination, and the right side of the picture shows some open seams that have not been filled. I have wondered whether a mixture of sawdust and some other liquid, such as sanding sealer might result in a better color match. Any feedback or suggestions would be appreciated. Thanks.
Replies
Filler is never going to match 100%. Apply the complete finish on a sample and then see what you can do with burn-in sticks.
John O'Connell - JKO Handcrafted Woodworking
Life is tough. It's tougher if you're stupid - John Wayne
You can also use the dust mixed in clear shellac, as this will give the lightest possible repair. Burn in sticks are also a good way to go, but you may need to melt two or more colors together to get a good match. A perfect match most likely won't ever be possible.
Try a test to see how it will look with a clear finish on it. Wipe the area that is filled with some mineral spirits - while the wood is wet, you'll get a very close approximation of how it will look after the finish is applied. The difference in color may seem less drastic - or it may be more pronounced depending on how the "filler" reacts. I'm guessing the filler may not change too much while the mahogany will take on a deeper color and the filler will be much less noticable. If so, do a sample of the actual finish to make sure you get the same results.
If the difference is still pronounced (or worse), I don't believe a different binder will have much effect as glue size is very effective as a surface sealer.
Paul
F'burg, VA
Ditto the suggestion to run your sample through the complete finishing process. If using solvent finish, I have heard that using the finish as the sawdust binder will make a near invisible repair. The comment said that water based finish as a binder is more likely to be noticeable.
Tough problem, but I have just had some success using dust from the sander-really powder-mixed with some epoxy. Maybe hard to do on a vertical surface an with deep seems. If you use the 30-second set stuff it will set up before it sags much. Though I have not tried it, a boat building friend uses the WEST system of expoxy and solves similar issues. Best of luck.
JK
While we often see the addition of any finish tending to make the wood appear slightly (or graatly) darker, there's often another component. You'll often find the degree of change depends on the surface roughness; try comparing 80 grit surface to a 220 grit surface, with the same finish applied. Now, the finer the sawdust filler you're using, the closer it approaches maybe a 600 grit finish. To change this, you need to change one or more of:
1- How fine the sawdust is. But a large change generally needed here.
2- The binder used. How effective depends on what you're using for a main finish.
3- The color of the wood. You might find a lighter piece of mahogany, or...
Can you tell the difference between mahogany sawdust and ash sawdust, other than the color? While I'll often do some toning later, I will typically pick some wood of a lighter color, then add a little bit of dye to darken it, leave a small bit dry to check the color match, then add a binder and go.
Gerry
When I have small spaces as you have shown in your photo, I use spare wood and cut thin slices off the band saw - if your have a band saw and it is well tuned with a good blade you can cut razor thin pieces. I use gap filling wood glue from Lee Valley along with the thin strips - takes a little time but the end result is far better than any filler combination. If done carefully, you will not notice the strips at all.
With some further thought, I remebered filling some gaps with strips made with a table saw. I put a few degrees of angle on the blade and ripped some fine strips. The key here was to make sure that the outside bottom edge of the strip was super-thin by making the cut so that the blade passed through the outside edge and the bottom face. I could flip the board end/end and cut again, but with the same edge to the fence, adjusting fence as necessary. I thought it would be lots of work to lay the stips in, but the sharp edges went in great with a few mallet taps. 5Min epoxy was enough. Hitting with the mallet really seated the strip-wedge really-and left no seams unless one knew where to look. Best of luck,
JK
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