I’m looking to use the film-forming finish above for outdoor projects. Uniquely though, I want to spray finish indoors in a well- ventilated paint booth supplied with make-up air, using HVLP equipment.
My initial application of the first coat of a two coat process has me puzzled. Three days after application , the first thin coat is still tacky, showing fingerprints. The manufacturer has told me that the reason is that the the finish is meant to be applied outdoors, but cannot explain why. I can think of only two reasons why my test has indicated a drying problem. Either the product contains an activator that requires UV exposure to cure, or the product has been exposed to below 0 degrees C before I received it. Has anyone experienced a similar problem with any water-borne exterior finish?
Grateful for any insight!
Replies
From Penofin: Trouble-Shooting A Sticky-Tacky Surface
Avoid overapplication by following the instructions we just covered. In the event of an overapplication, use the following methods to resolve.
To Remove Excess
Allow Penofin to dry for seven days.
Use Penofin Protech Cleaner and scrub the surface with a nylon or natural bristle brush. Do not use metal brushes.
You may also use Penofin Wood Stripper for tough jobs.
Allow the surface to dry for 48 hours before reapplying
The suggestion is that we applied a too thick coat. This is definitely not the case. We applied as thin an aerosolized coat as we could using an HVLP sprayer with the correct needle and air cap. The big question is why the mfr told us that the finish MUST be applied outdoors.
It sounds like way more trouble than it's worth.
You may be right but now it’s a matter of just wanting to solve a chemistry question.
In search for years of the best outdoor finish grail, lol. The ideal would be a finish that doesn’t totally distort the natural colour of “0iled Teak”, retains that appearance for 1-2 years on horizontal surfaces, resists mold, at which point maintenance only requires cleaning, light scuff sanding and reapplication. WITHOUT the need to strip to raw wood. One or two part finishes are OK. In over 25 years of testing, NO penetrating finish works without too-frequent reapplication. Hence the search for a film-forming alternative. Product cost is not a significant factor. It’s all about minimizing labour.
You mention “film-forming” finish when it’s actually a penetrating finish. You also say you sprayed a thin coat when Penofin says use a brush or pad. You didn’t say you wiped off the excess when Penofin says you should. Sounds like operator error. More from Penofin Q&A: “Do I really have to wipe the wood after applying? or... My deck is sticky, tacky, shiny, dark, the smell won't go away, its been two weeks, "My Dog is stuck to the deck!!!!!!!", "My son is stuck to the deck!!!!!".
This is the grand daddy of all application questions and the answer is a resounding. YES...!!! Penofin is a penetrating finish that penetrates into the surface of the wood. That is where it belongs and does it's best work. The surface of the wood must be wiped thoroughly with nap free cloths to assure that no Penofin dries on the surface of the wood. If you allow Penofin to dry on the surface of the wood it will turn sticky and tacky and eventually peel off the surface because it is not a surface coating. It will also interfere with the cure of the product that has penetrated into the wood causing the product to fail to protect the wood fibers.“
Thanks for your reply Eddo.
I notice that your quote from the Penofin site FAQ does does not
directly reference the TSF Architectural product I am testing. It just states " "Penofin is a penetrating finish", and of course, Penofin is the company name, not the specific products like "Blue Label", "Hardwood Formula" etc.
The reason I thought TSF was different than a strictly penetrating finish, is that in the "Application Tips" for TSF, it states under "Coverage" that "Two thin coats are required". Perhaps they don't intend "coat" to imply any surface residue remaining as I had assumed it did. I do see that it also states "Remove excess coating with a dry pad applicator, brush or roller and evenly distribute the finish".
I assumed that since I sprayed a very thin coat by HVLP, that my film thickness would equate with a heavier rolled application which is back-brushed.
There is also a statement in the same instructions referencing "....the coating's film". The word film, to me, suggests a thin surface coating, not a surface "wiped tight" as is done with finishes like boiled linseed or tung oil as applied to furniture in a classic "oil finish".
My next test will be to purchase a new gallon of TSF, which I have been told for certain has never been exposed to cold temps, and apply it as I have already done on two fresh substrate, one left to cure as before, and one immediately "back-brushed" with Wooster #F5119 Bravo Stainer Brush which I will also purchase specifically for this test.
I'll report back!
Thanks again for your input.
What were the results of your second test? Thanks
You might be partly right about the Architectural being slightly different. The product sheet lists a wet and dry mil thickness. As for application they do say you can spray it, but then they go on to say to “immediately back-brush or use pad applicator to eliminate puddling. Remove excess coating with a dry pad applicator, brush or roller and evenly distribute the finish”. Good luck! Here’s the Architectural product sheet: https://www.penofin.com/pdf/ds/ds-penofin-architectural-grade-hardwood-technical.pdf
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