Glue bleed through burr oak

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21 Mar 2017
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I have just veneered a small box in burr oak using cascamite. Unfortunately a few areas of teh burr had some small voids which filled with the glue and when cleaned up these show as white patches. Is there any way of treating these?
I've never found one that is stable enough, Trevanion. They've all faded away to nothing in a year or two in my experience. I even bought a series of them at a woodwork show once which were designed for exactly what you propose, and the filler they once covered on a settle I made stares at me, bright white, every time I go near it.
I'm not sure there's anything you can do about Cascamite bleed through; the stuff sets glass hard so I can't envisage anything that will touch it. Custard might know a trick or two though - Rob
There are loads of different tricks for patching burr veneers. But the fact is you'll probably have to do some remedial work on the majority of burr veneers you use, so either go into the job prepared for that...or stick to plainer veneers!

Tiny pin prick holes are often filled by the moisture from the glue swelling the fibres and closing up the hole. One of the side benefits of hammer veneering with Scotch glue is you get this effect automatically. Another way of maximising this effect is with vac bag veneering, the vacuum pulls the glue deep into the pin hole and swells the fibres that bit more.

For larger holes and voids you're probably best patching. Start by covering the hole ON THE FACE/SHOW SIDE with masking tape or even sellotape. Then flip the veneer over and work from the BACK/GLUE SIDE, filling in the void with a knifed out patch or patches cut from scrap sections of the same veneer. Basically you want to patch using the darkest bits you can find. Hold them in place with a bit of PVA rubbed in with your finger. It's one of those techniques that all comes good in the final finishing, so have faith and stick with it, the final result will look better than the interim steps.

You can use special veneer hole punches, either bought to shop made. Every professional veneer workshop has loads of these but you'd be surprised how often full time veneer laying craftsmen just knife out their patches with a scalpel.

Another common solution, especially for smaller burr veneers for things like side tables or boxes, is to tape the flattened veneer to a window with the glue side facing you. You can then mix up a stiff blend of epoxy coloured with earth pigments to a match the darkest shade naturally occurring in your veneer. Fill the voids, flatten off, and lay the veneer once set. Again, you'll be surprised how effective this technique can be.
Hornbeam":3uf52qx8 said:
... burr had some small voids which filled with the glue and when cleaned up these show as white patches. ...
Is there any possibility of cutting back the glue in the voids with a small rotary burr & dressing the undercut areas with a better matching dust/glue paste.*

* I find fine sanding dust mixed with medium CA glue a good quick drying and hard filler.
Make the Cascamite brown before using by adding some Van Dyke crystals to your mixing water. You can play around with the colour saturation to get the required shade. Experimentation is needed to get a feel of the process.
Believe it or not, fade resistant spirit stains from Chestnuts will work with Cascamite as well, a few drops added to and mixed with the powder before adding water works fine for me, have not detected any loss of bond strength when turning.

The volatiles disperse quickly and any remaining would appear to be water miscible.
Thanks for the comments. I will try cutting back with a small dremel burr on a less visible area. Its only a couple of small areas which I missed during veneer prep.
CHJ":msgn0jtf said:
Any news about the outcome, success, fully or partial?
I used a a small phillips screwdriver ground to a very sharp point. Although cascamite is hard it was also brittle so OK to crack out of some of the small fissures. There was nothing bigger than about 2 mm wide and all very small. Have filled the gaps and very pleased with result but will reserve final judgement until final polish. If I had used a dark glue in the first place it wouldnt have been an issue