Stabilizing Redwood burl
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ironman123
Member
what JIM said.
Ray
Ray
I'm doing a 3x3x7 chunk now with some buckeye burl for an experiment with Ed. I'll slab a chunk off and see where we're at. FYI, I'm using Curtis's big tank, 27.5"mg with a HF vacuum pump. Just pulled it for an hour, resting for another hour then in the oven at 210* for a couple hours. Internal temp must reach cure temp, I aim for 200* although cure temp is a bit lower.
Happy to answer any questions I can.
Happy to answer any questions I can.
Funny, I just watched his how to video again last night. I noticed he said only 45 minutes in the oven. I've always had to leave mine in for at least 2 hours. I set the temperature at 200. Higher and I've had problems with the juice boiling out.
Of course, I'm sure none of the ovens we are using are calibrated very well, so your setting will vary from mine.
Of course, I'm sure none of the ovens we are using are calibrated very well, so your setting will vary from mine.
MesquiteMan
Retired Head Moderator
Be aware that the video is around 3 years old now. A lot has been discovered in the last 3 years. There is no rule of how long to leave in the oven. It depends on size, mass, density, etc. The resin itself, only takes 10 minutes to cure once it reaches the critical temp. The unknown variable is how long it takes your particular run to get to 200° F core temperature. Temperature is important since hotter temps will cause more bleed out. Oven dials are inaccurate, thus the reason I highly recommend using an oven thermometer to set the temp.
MesquiteMan
Retired Head Moderator
Oh, and redwood burl is more difficult to stabilize than other woods. The same applies for most all softwoods (by definition, not actual hardness). The cellular structure of softwoods is completely different than hardwoods. Redwood burl is one that benefits from an extended soak after pulling vacuum until the bubbles stop. I have more than doubled the weight of redwood burl so it certainly works.
Ha!!! Yeah Steve...that's a big variable. I do a lot of food smoking and have some really good thermometers. I was able to dial mine in real well. Right now, there are four Buckeye burl pen blanks and a big chunk of redwood burl. Buckeye will sit for a couple hours...redwood, no idea so I'm going to let it sit 4-5 hours. Better to go to long than to little with stabilizing!
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Curtis, I ran this under vacuum for an hour and no more bubbles. Let is sit for another hour at ambient air pressure. Now...in the oven at 200* according to the Maverick temp probe. Right along the lines of what we've talked about. I'm going to cut the redwood into stopper size blanks when done so we'll see if I got it right!
MesquiteMan
Retired Head Moderator
Jim,
My recommendation now is to let the blanks soak at least twice as long as they were under vacuum. The resin uptake occurs AFTER you release vacuum and since it is MUCH thicker than air, it is going to take longer for it to get back in and the pressures to fully equalize. The little bit of redwood I have done were soaked overnight.
Sabaharr
Member
First, I use Cactus Juice exclusively. For any burls I have left the vacuum on and gone watch a movie, sometimes 2 movies, and still see a little trickle of bubbles coming out. As for soak time it is overnight. I have done some time experiements and marked the level of the resin at start, one hour, 2 hours and overnight soak. I have found that the blanks will almost double there abvsorbtion of resin overnight that they take in in just an hour. It uses more resin than I would like but the point is getting it into the wood. So in my opinion the soak time in more critical than the vacuum time. You can see how much air is coming out when you vacuum, you can't see the resin going in during soak. Try marking your container by putting a piece of masking tape on the side and drawing a line at the levels at various periods of time for various types and specis of wood. Keep a record and you will be amazed at what you see. I did some 6 inch long by 1.5 inch maple round pieces a fe days ago. Eight of them sucked down 1.5 inches of resin in a five inch diameter container overnight. Thats a lot, about 10 ounces. At an hour it was only about 4 ounces. At little data gathering will tell you a lot. FYI, I build satellites at NASA so I tend to overanalyze EVERYTHING.
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steve worcester
Member
DRY Redwood is super porous. Personally, I leave the blanks under vacuum until I see no bubbles, then leave it soaking (no vacuum) for a good long while.
If the product cures at 200, and it is thick, the outside may be at 200, but not the inside. I don't think wood is a good thermal conductor. But you can leave it in there longer under temp to get the internals at the same temp as the externals. It likely doesn't break down until it gets to greater temperatures (Curtis, chime in here, can you over cook?)
The time is going to vary greatly based on thickness. a solid 1" will take less time than a 6" block, maybe considerably. If you can accurately control the temperature, I think you can leave it at the process temp for a long time to equalize internal and external temperature as long as you don't go too over temp (don't know what that is). I am fortunate enough that I use computer controlled glass kilns for this and can hold it at about 10% for how ever long I want.
If the product cures at 200, and it is thick, the outside may be at 200, but not the inside. I don't think wood is a good thermal conductor. But you can leave it in there longer under temp to get the internals at the same temp as the externals. It likely doesn't break down until it gets to greater temperatures (Curtis, chime in here, can you over cook?)
The time is going to vary greatly based on thickness. a solid 1" will take less time than a 6" block, maybe considerably. If you can accurately control the temperature, I think you can leave it at the process temp for a long time to equalize internal and external temperature as long as you don't go too over temp (don't know what that is). I am fortunate enough that I use computer controlled glass kilns for this and can hold it at about 10% for how ever long I want.
MesquiteMan
Retired Head Moderator
Cactus Juice will not just cure on the outside and not the inside. The entire piece of wood needs to be at 200° F before polymerization occurs. Hotter temps will NOT hurt the Juice, it will just cause more to bleed out before polymerization. I have cured at 400° F just to see without any problems other than excess bleed out. Also curing longer will not hurt anything. I have left blanks curing in the oven for 5 straight days by accident. Didn't hurt anything but my wallet! Once Cactus Juice cures, it is heat resistant to 400° F. I frequently leave my blanks in the oven overnight just because it is convenient for me.