Skip the pretreat spray, use denatured alcohol on oily woods before glue-up

I used to fight with teak and ipe for years, wiping with acetone and still getting joints that failed after a few seasons. Last spring on a deck job in Charleston I tried denatured alcohol on a rag right before spreading the glue, and the bond held way better than anything else I tested. The alcohol dries fast, cuts the surface oils without leaving a film, and it costs about $12 a gallon versus $20 for a small can of special prep. I did a side by side test with two offcuts, let them cure a week, and the alcohol sample split the wood grain while the acetone one peeled clean. Now I keep a squeeze bottle in my apron for any exotic hardwood, and it saved me a redo on a $4,000 railing project. Has anyone else tried this or do you stick with the commercial degreasers?

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paigeharris14d ago

That "split the wood grain" part is exactly what sold me on this trick too. I had the same thing happen with some old-growth mahogany that kept failing at the glue line no matter how much I scrubbed it. Tried denatured alcohol last year for a curved staircase stringer and the joints held through a whole humid summer without a single creak. Acetone always felt like it was pulling moisture into the wood somehow, even though it dried fast. The alcohol just seems to lift the gunk without soaking in weird. Now I don't even bother with the fancy prep stuff, it's just alcohol and a clean rag for me.