Trad Gang
Main Boards => The Bowyer's Bench => Topic started by: Oosie on September 29, 2016, 02:58:00 AM
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I apologise if this question has been asked before, I could however not find it in the forum.
I am having difficulty understanding Smooth On's curing and characteristics. :help:
Smooth On cures at room temperature in 24hrs?
Some people use an "oven" to cure it in 6hrs?
Smooth On's instructions state that after cure (24hr or 6hr oven) it can be heated for 6 more hours to enhance the properties?
So now my question is this:
Room temp 24hr = Oven 6hr?
Room temp 24hr + 6hr tempering = Oven 6hr?
What is the best practice regarding smooth on to eliminate delaminations as far as possible? :help:
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Testing has been done buy bowyers and the findings where that the 24 hr. cure then heat cure yielded better bonding. In test strips they tore apart showed more actual wood being ripped to get the pieces apart. What you do not want is for the glue to get too hot before it has a chance to soak in to the wood or get all the air squeezed out. I leave mine under pressure at least two hours before putting in the hot box.
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Originally posted by Crooked Stic:
I leave mine under pressure at least two hours before putting in the hot box.
So you do a 2hr room temp cure followed by a 6hr oven cure and I assume a gradual cooldown from oven temp over the next 16hrs?
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Yes on the gradual cool down.
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If you ask ten guys you may get ten different ways of gluing up a bow...
Here's my method on gluing up a bow... Glue it up for 5 to 6 hours at room temperature and then stick it in the oven for 5 to 6 hours at 150 to 160 degrees...
Here is why and how I do it...
Any extreme fluctuations in temperature is hell on wood... If you put your form in the oven it may warp on you... I had one warp on me... So I put my bow in the oven afterwards without the form... Some may argue against this saying your bow may warp or twist... Trial By Fire I call it... If your bow is gonna warp from the heat let it happen now and not a year from now in a hot car... Another reason I do this is because trapped air in the wood, joints and any air bubbles will expand when heated... Meaning that it could create voids in your joints... Curing epoxy at room temperature will probably be plenty strong enough... But you want it fully cured... Some resins could take a week or two to fully cure at room temperature... So heating it will speed up the curing process plus the added benefits of supposedly a stronger bond... I also read that breathing in uncured epoxy dust can be very harmful...
I also only pump my air hose up to 38- 42 psi... Epoxy is not wood glue and too much squeezed out of a joint will leave you with a dry joint...