On Sunday, October 22, 2017 at 2:50:48 AM UTC-4, snipped-for-privacy@gmail.com wrote: Rob:
My hunch is that DadiOh is on the right track-- especially if this is in fu ll sun, the Sun's UV will break down that wood with a reasonable amount of speed... But a week's a little quick.
However, just to check-- you said "cloth." How often did this cloth get we t? Did the cloth retain any moisture? Moisture, in the form of water, oil , (or the protectant that you're intending to apply, for that matter) will darken wood.
I would recommend first, get the cloth off the table; second, make sure th e teak is completely dry. Completely. Use a hair dryer (or heat gun on L OW and pulled WAY back from the surface-- about 2 feet+ if you use the gun) to see if that darkness disappears with heat. If so, do not coat the surf ace until that moisture is gone.
Regardless, yes, you should sand the surface prior to coating. Often thing s called "bare wood" coming out of furniture plants are still coated with.. . something to help protect them while in the company's possession. It cou ld be a waxy or quick oil coat. I've even seen thin plastic-y veneers used for this purpose. if you don't scruff that stuff off, you'll get an uneven , blotchy finish-- if your finish sticks at all. In addition, if DadiOh i s right, and the surrounding lighter tone is from UV breakdown, then you ne ed to get through that graying dead-wood fiber to get your coat down to the good lumber you're intending to coat.
For an outdoor teak table, no need to go any further than 120 or 150 grit p aper WITH the grain (goes w/o saying) and I wouldn't go to a power sander o f any variety fr this. Just scruff the surface until you see color get r easonable consistent throughout (with tolerances for grain and different bo ards of course.) If you run into plastic or wax, keep going until that's go ne-- plastic you'll see pieces peeling upward from abrasion and heat; wax w ill clog your paper with sticky residue pretty quickly. Get all that dus t off of there, and then coat it with a quality oil--
The object is teak; I'm assuming that you'll have it in sun or water per th e above comments and from your original post-- the word is QUALITY oil. Do n't go to Thompson's for this.
You'll need to recoat this item fairly often in the outdoor environment, as suming full/partial sun and moisture. Tung Oil and Boiled linseed oil (AVO ID the RAW Linseed Oil at all costs for this project) are both traditional teak finishes but you need to make sure that the one you grab is rated for outdoor/exterior use. Additionally they often need to be recoated more of ten. Anything that calls itself "X Oil FINISH" has other ingredients in it ; it may add a sheen. If that's what you want, then that's fine, again, ju st assure yourself you can use the stuff outside.
Avoid "teak oil" 'cause you can't tell what it's really made with from manu facturer to manufacturer, and it's usually marketed at a higher price point to "teak consumers" even though it's little more than a combo of the above two.
I've had good success with General Finishes Outdoor Oil for teak & cedar-- decent UV and great water protection. Cabot Australian Timber Oil's line i s good as well. For my money and time, I'd go General for this project-- it lasts longer than the traditional products and is a little more viscous than the Aussie.
There are also a bunch of other "Just fine" products on the market for what you're doing-- there's honestly not a lot of precision required on this pr oject. But there's even more junk, and the junk is usually the first thin g that someone can put their hands on at a big box store. If you've already picked something up, post it here, and someone will definitely get back to you with a metric from 'quality to junk.' If you don't have anything yet, head to your nearest Rockler, Woodcraft or other local quality woodworking shop. Finally, I've seen a lot of slatted teak tables recently-- not 6" x 2" boar ds you'd see on a traditional picnic table, but instead about 3/4" x 2" sla ts with another 3/8" to 1/2" of space between them. If your table looks li ke this, don't forget to do the sides of these slats. Saturate a rag in yo ur finish, floss it through the slats, and make sure you get those sides. (...then dry/dispose of the rag according to our knowledge of finish dispos al-- any of these products has the potential of spontaneous combustion.)
Good luck-- Hope that helps.
S