Replies

1. 
   pantalones868 | Apr 23, 2025 12:19pm | #1

   The windows were new never before finished? Even if brand new I would think they were sanded after assembly,milglaze is unlikely.
   Watco teak oil is a polymerized finish not a true oil as such. In my collection of finishing materials there is a whole section of Watco products. I write the date of purchase on the cans and I have discovered that some of the newest stuff , like Danish oil, has gone bad on me. Old ancient can still good ,new stuff bad! I suspect it has something to do with reformulating to meet voc requirements but then how do you know? So, that's one possibility. Gummy surface would most likely however be the result of letting it sit too long after application before wiping it down. Also, are you absolutely sure that your mahogany windows are true mahogany? Until you start using latin names many types of wood get called "mahogany" when in fact they are something else. True mahogany? Then you bought some damn expensive windows! Solid or veneered? I've never experienced tannin bleed as you describe with mahogany. Woods in general will tend to darken some or even alot when oiled. If these are exterior windows, like on your house I wouldn't think that Watcos would not be a particularly good choice in any case.
   If these windows are not new then they have most likely been finished before. So you have the possibilities of poor surface preparation and or a chemical reaction between two incompatible finishes.
   This happened to me not long ago refinishing a teak table. I stripped the old finish and started by refinishing the legs and they came out looking good but when I proceeded to the top there were areas that the finish apparently hadn't been completely removed resulting in a really blotchy appearance. Oils penetrated in some areas looking dark and no penetration in other areas-- improper surface prep and I know better....simple job got suddenly really difficult!

2. 
   Cindisan | May 05, 2025 08:21pm | #2

   It sounds like the Watco teak oil is interacting with the tannins in the mahogany, causing the wood to darken. This is a common reaction as teak oil can sometimes exacerbate the tannins. The gummy texture might not be milglaze, which usually appears as a waxy buildup from insufficient sanding. To fix this, try gently sanding the surface and cleaning it with mineral spirits to remove the excess oil. In the future, consider using a finish specifically designed for mahogany to avoid similar issues.