Adding Ultraviolet Absorbers to Linseed Oil
Tips on adding ultraviolet light absorbers to linseed oil or modified tung oil for use on exterior wood doors. August 25, 2008
Question
I have used BLO to finish a few exterior doors and they continue to look great. My question is if anyone knows if it is possible to add UV absorbers to BLO? I did a quick search on Google for UVA suppliers and found Horizon Specialties that sells benzophenone, although I am not sure in what quantities. Surely it is not that easy. Just add benzophenone and BLO in the proper ratio and presto, instant finish with UVA. Any help anyone has is greatly appreciated.
Forum Responses
(Finishing Forum)
From contributor C:
Benzotriazol's are much better - contact Ciba Geigy for a sample of 1130 inhibitor and try it. Ciba is a leader in UVH and HALS additives - I use very few others.
From contributor P:
Could you tell me what BLO is, as I finish exterior doors. Also, is this finish equal to or better than a cat polyurethane?
From contributor C:
BLO stands for Boiled Linseed Oil and no it's not anything like CV or 2k urethane. It would be my last choice for doors. Polytung is much better and more durable than BLO, but to each his own.
From the original questioner:
I agree with BLO not being a great exterior finish, but the doors it has been put on are very well protected and the clients insisted on not having a plastic looking film finish. They reapply or hire me to reapply a fresh coat every 6 months.
From contributor P:
Thank you for the info. I didn't realize it was that simple. Contributor C - what would be your preference for a exterior grade finish? We use 2k urethane for all our exterior entry ways and have been happy so far. Again thanks for the info.
From contributor C:
I have to agree with Contributor A as to oil finishes. I use polytung with UV inhibitors and Hals on the bare wood to stop fading or darkening depending on the species, and yes it requires re-oiling often to keep the appearance up especially if sunlight is falling on it every day. I never have to strip it or worry about it cracking, etc
From the original questioner:
To contributor C: I hope you don't mind me picking your brain for a little bit. I requested a sample of 1130. I haven't read the technical sheet yet so I may find my answer, but do you know what ratio 1130 to BLO?
My second question is, in reading the brochure, what is 1198? Is that something that can/should be used with 1130? Not quite understanding the difference between the two.
From contributor C:
1130 if I remember correctly is 3% by weight to the blo, the 1198 is about the same 3 to 3.5 %. By weight the 1198 is a hindered amine light stabilizer to be used in an aqueous solution on the wood itself and it can be used in conjunction with the 1130 for better overall performance. This is what I use for my polytung finishes for longer term protection than just the UV inhibitor by itself. Ciba recommends both.
