Hide Glue Filler?

[Erik Hokanson]

1. Anyone ever mix hide glue with fine sawdust and use it as a filler? Is this a stupid idea? I've done it with epoxy, but is there some traditional filler I need to know about?
2. Can one just add water and granules to my gluejar as needed? There is this whole ceremony to make the glue where I'm supposed to let the water soak into the glue before heating, why cant you just put together the appropriate proportions, put it on the heat and when everything is all melted and hot, it's good to go? There may be something I'm not considering about this.

[Steve Senseney]

Hide glue in a "lump" will absorb water, and swell and shrink a little with the seasonal humidity changes.

It can easily crack.

I have not used it to fill a defect.

If have used it extensively to glue in a chip of wood which might get torn out, or repair a defect with solid wood replacement.

If I needed to fill a cavity, I would use a chisel, make a nice filler piece, and hide glue the repair in place.

[Stephen Bacon]

I have had success with high strength/ high grade hide glues (300+) and wood flower( table sawdust). Lately I have been experimenting with the silica filler I use with my west system epoxy. It is very bondable, very strong , no noticeable shrinkage. I seal my work with light spirit varnish. I live in a dry climate, but have some samples sitting in my high humidity chamber, no problems yet.

[John Hamlett]

As I understand it, it is best, when making filler, to use mostly wood dust and minimal glue/adhesive/epoxy. I mix the dust into the glue until it will except no more dust. At that point, the filler is more wood than glue/adhesive/epoxy, and I feel like it becomes less important what the glue/adhesive/epoxy is. I prefer epoxy for several reasons, the main one being working time. I suppose, in a room at 90 degrees Fahrenheit or so, hide glue would work fine because there would be plenty of time to mix the filler, but I would expect more shrinkage upon drying that epoxy, and probably more movement in response to moisture content down the road.

[Erik Hokanson]

Thannk you. I will try this. Im just getting all purist about materials, i know epoxy is probably best for this, but i like the idea of hide glue. Im glad its doable. I will report my results when i do it.

[Mark Swanson]

That is interesting John. Others that use epoxy for filler have told me to use only enough wood dust or matching colorant as needed to get the right color change. Some use no wood at all but just a tint or dye to color the epoxy until it matches. When using wood dust, there are problems with it drying a darker color, so sometimes it's best to use a slightly lighter dust for the fill. Test this on scrap for the best match.
If you want to use hide glue, then you will have to make a mix of the dust and glue in a pot or container that will keep it all hot, otherwise the minute you add the dust it'll cool and won't work. So mix up your glue/dust in a heated container, then apply it quickly. I like to cover it with a piece of tape right away, and then push down on the tape to force it into the gap...after it's dry remove the tape and sand it flush.

[John Hamlett]

Mark, I once had to finish a walnut burl banjo resonator. There were lots of small voids that needed to be filled in order to have a smooth surface. I filled the larger ones with the dust/epoxy filler and the smaller ones with stick shellac. I saw that resonator some time later (couple of years?) and all the fills were still looking OK, but the dust/epoxy ones were the smoothest, in fact they were still virtually perfectly level with the wood surface. I've since operated on the assumption that dust/epoxy is a stable filler when mixed to a hard paste so it is mostly wood dust.
As for color, yes the filler is darker, and dries and finishes darker than the wood the dust is made from, so I treat it a lot like mixing paints and pigments. I use walnut sapwood and walnut heartwood to mix a matching color for walnut, for example. Maple, cherry and other light and dark woods are all on my potential "palette" for mixing filler to match whatever wood I'm working with.