24 April 2016 at 6:20 pm #136648George FulfordParticipant
I made this laptop desk a few months back and have run into a problem. I finished it with 3 coats of 50/50 wipe-on poly, then 2 coats of full strength poly. What’s happening is the heat from the laptop computer that sits on this desk is weakening the finish and making the glue joints separate. Does anyone know of a good heat resistant finish?
You must be logged in to access attached files.24 April 2016 at 7:56 pm #136659Matt McGraneParticipant
I have no specific experience with this, but after thinking about it maybe an oil finish would be appropriate. It’s just a thought, but I would guess oil would handle heat better.
But now that I think more about it, probably the heat is causing the wood to lose more moisture in higher heat locations. Seems like the best finish to keep that from happening would be one that seals the wood the best and I don’t know a better one than polyurethane.
Matt, Northern California - Started a blog in 2016: http://tinyshopww.blogspot.com/25 April 2016 at 8:18 pm #136692EdParticipant
This may not really answer the question, but it will address the problem…use a cookie sheet. I had a laptop than ran hot, so I always put a cookie sheet underneath. It acts as a heat sink and helps cool the machine. You want a flat sheet, not one of the fancy ones with lips around the edge.
For the finish, your best bet is to pick your favorite finish manufacturer and send an email to tech support, or call. There should be technical data sheets, but calling is best. They may direct you to something you cannot apply, e.g., because it requires spray equipment, so make sure you can apply whatever they suggest.
If the heat is causing the glue to let go, though, I think this isn’t a finish problem and you need a cookie sheet.29 April 2016 at 5:32 am #136796George FulfordParticipant
Thanks for the help 🙂 Guess, I’ll be getting a cookie sheet in the near future 🙂30 April 2016 at 6:10 am #136826M WParticipant
Many glues used in woodworking will start to creep/flow above 125° F. PVA and Epoxy will both do this. If you ever need to disassemble a pva or epoxy joint, judicious use of a heat gun is invaluable.
It also looks like there are different species of wood in your top. Although woods in general expand and contract at the same rate, grain orientation and different species will minutely be different from the adjoining plank. To exacerbate this, if you used a hard glossy poly, it is a relatively brittle film, excluding spar varnishes. So as the top goes through heat and cooling cycles, it may fracture the poly film and allow greater moisture ingress at the joints swelling the edges of the planks.
If the aluminum sheet idea fails, maybe use plywood or plywood with veneering. Plywood expands equally in all directions if it is a balanced veneer (equal number of alternating veneers).
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