Speeding Up Poly Curing ?

[Spinzwood]

This question is tied with the question posted earlier about Sap/Veins in Wenge. I finished turning my Wenge handle for my son's shaving brush.. out of Wenge. I tried to see if Minwax stain (oil based) would stain those veins.. (It didn't.. but the stain looks nice on the Wenge).

I applied the stain per instructions and let it sit for about 15 minutes and very thoroughly wiped it off while spinning slowly on the lathe. After that, I took it off the lathe and put it on a sleeve of paper towel and further rubbed the stain until nothing came off on the paper. Then I let it sit for 24 hours.

Following that, I added a coat of Minwax Wipe-On Poly, evened out the finish the application rag and let it sit in my house (it's warmer) for 24 hours. It still felt "tacky".. not so anything would stick to it.. but, like it hadn't cured.

Instructions say to let it sit for 2-3 hours before sanding. It's been over 24 hours. Well, I buffed it with 0000 steel wool and applied a 2nd coat. This one has been sitting for 24 hours and still feels sticky.

I called Minwax and asked about this and they said to let it cure longer.. maybe up to a few weeks.. There goes the Christmas present.. possibly.

So, to the question.. anyone know how to speed up the curing of the poly? It "could" be the stain underneath.. but, again, according to the instructions.. I should have been more than golden.. at every point. Life is giving me lemons..

Oh, forgot to mention I tried hitting it with my woman's hair dryer.. even tried a few 10 second blasts in the microwave.. that was not a great option.. wood split and I had to CA to fill the gaps. How do I make lemonade?

 

[greenmtnguy]

10 seconds in the Microwave should not make it split. I do green wood for 1 minute blasts in the micro to speed drying. I wonder if the wood was not fully dried and the stain and poly have trapped moisture inside the finishes. Possibly that is why the wood split. Trapped moisture turned to steam and pressurized the core of your blank. The 10 seconds causing a split still puzzles me. What size was the blank at starting point, and roughly at finishing?

 

[leehljp]

I have used wenge before on several occasions, and did not notice any sap those times. I was unaware that wenge had sap like that.

That said, there is something wrong for sure. I have had different paints, maybe 2 or 3 times at the most over the past 40 years, that for some reason took forever to cure. I know that applying some enamel finishes during high humidity times caused drying times to be extended over a couple of days.

I would get some acetone and take it off as best I could and refinish with some fresh coats from a different can of finish.

 

[Spinzwood]

Hank.. it was a furniture grade kiln dried wood. The turned part was the handle for a shaving soap dish... so, size is roughly bottle stopper sized. It cracked along grain lines.

Also, I'm calling it "sap". That may not be a correct term. But, as I look at online descriptions of the wood.. these cream colored inclusions are a part of the type. Some may/may not have it.

 

[greenmtnguy]

Were the stain and finish both water based or both oil based for compatibility? Still can not figure why 10 seconds would cause it to crack. Especially kiln dried. Hopefully more experienced users of Wenge will chime in.

 

[Spinzwood]

Alton.. not sure why either. I wonder if it is possible that the white flecks, bands remained solid while the wood slightly moved during the microwaving. Despite being kiln dried, there is a lot of moisture in the air at this time of year. That will definitely move into the wood. The cracking is not like you would see in a log/branch where it is a radial split. This fractured along the grain line.. It happens, due to the nature of the "wood" when I am carving cottonwood bark. Picture taking an axe to a log while splitting.. Not splitting thru the center.. rather taking the log down by knocking an edge off.. popping off a few growth rings on one edge at a time.. That's the only way I can explain it.

Someone at the turning club suggested it might be the age of the Minwax Poly.. I can't remember if it is a new can or older. I should date the purchases

 

[jttheclockman]

Hello again Bill

I will try to help you but you are the one that needs to experiment. Whenever working with woods you are not familiar with it is always best to try different finishes on scraps of the same wood. But what I mean by that is you need to prep the wood the exact way you would if it were the final piece.This means sanding the scrap wood, adding shellac, tinting with stains and so on. So that when a finish is applied no surprises will crop up.

Now the wood you are working with is hard to tell what it is. Many people come here and show small pieces of wood and want us to miraculously tell them what the wood is. There are various wood Data bases on the net that give fairly accurate photos of many woods from around the world. With that said though not all boards are alike. Can be same species but look totally different. Try to work with woods you know at all times.

Now you mention Bubinga and Wenge. Both these woods are highly splinter oriented and if you get a splinter working with them, get it out right away. It will get infected quickly. They are also woods that the dust can be a hazard so be warned. I posted a few photos of boards of each. The one on the right is bubinga and it is more reddish in color and streaks of lighter grains. The one on the left is Wenge and it is darker with more pronounced light streaks of grain. These are not sap wood. I also included a quick shot of each board with some denatured alcohol on it to resemble a finish somewhat. I did not want to contaminate these boards because they are not cheap and I use them for other projects, but you get the jist of the look.

Now to your question and my suggestion and it is only this man's opinion and I have to say that because one reason I do not come here much any more is because I have had confrontation with people here about what I say.

Whatever wood you have is an oily wood as I told you this before. When you get project to finished stage you need to wipe it down with acetone before doing anything and that includes using an oil stain as you did. Wait for it to dry which is about half hour. Stain if you want. Now you have introduced oils back into the wood unless you are using a waterbased stain. No matter. Need to let this dry and cure which is 24 to 48 hours in a warm and dry environment. No nuking or ovens!!!!! Now you need to decide the top coat. CA, Poly, or Lacquer. I will tell you this I have used Danish oil on this wood and polished to a soft sheen. Always looks good and feels good. Again though the pores of the wood are not filled so you will see this and feel it. Now if you are going to put poly on top which you did I suggest you apply a coat of dewaxed shellac under it. This will separate any oils from contaminating the finish. I like Bullseye dewaxed shellac. Can get in wipe on or spray. I like spray because it will not leave streaks like a wipe on can. Then after you followed on the can instructions for drying and curing, proceed with your poly. I never like poly, much prefer lacquers. But this depends on the use so I will leave that to you. Again let dry and cure before use. As always make sure your materials are fresh and stored properly. Also remember safety when it comes to oil and rags. They can combust so beware. Good luck and hope something in here helps.

 

[Spinzwood]

Thanks, JT.. there is a lot of good info there..I really like the idea of experimenting with the wood and finishes before turning. You can always turn that material off after you make your decision..

Re people confronting you. I have that problem all the time. I just say thank you and move on. Who knows if they are having a bad day or are always a confrontational, highly opinionated _____ (fill in the blank). What you have provided me with is very helpful information and I thank you for taking the time to do it.

Same thanks to Alton and Lee.

The finish feels a bit better today. I was thinking of taking acetone and stripping it all back and starting over.. Today, I think I will put it back on the lathe and buff with 0000 wool and let it sit one more day.. or two. There is less odor.

Because it will be used as a shaving brush and is destined to get wet... I'm looking to completely fill the pores. So, I'm guessing a few coats of poly will be in order. Because it is essentially "all" end grain with the exception of the less than half of the major OD's. I'm expecting a lot of absorption of the poly.

 

[JimB]

Ive used the Minwax Wipe -on Poly on some pens although I haven't done one in a long time. When I did I found the first coat of WOP took a long time to cure... 48 to 72 hours. Heavy coats will take even longer. After that the other coats were more like 24 hours. The best thing to do is very thin coats. I also found humidity to be a big problem and it would take forever for it to cure. We don't have A/C so if was humid outside my basement shop was also more humid.

 

[Wildman]

Like JT said wiping down with acetone before applying a finish/stain a good idea, apparently Wenge has an oily surface but dense very porous wood.

Because a porous wood a sealer coat recommended, guess whatever use must be dry before applying top coat or else end up with a gummy mess.

Fully cured times lot longer than recoat times. Think for oil poly finishing products fully cured times runs about 30 days at 70 degrees F. Depending upon product directions might see 24 hours before light or normal use.

Have only used MW oil based poly on about fifty pens and stopped using it and switched to making my own 50/50 (poly/MS) mix wipe on poly.
If check out section 3 composition/info on ingredients on products SDS, consist of 70% MS.

http://www.minwax.com/document/SDS/en/US/027426409002

Only problem have with MW oil wipe on poly is amount of MS to resin, takes longer to get a build of finish on the wood. At same time should dry faster I think, but just not on Wenge.

Facts about oil base wipe on poly's two coats of 50/50 mix equals one full coat of oil poly. If increase amount of solvent/thinner takes more coats to achieve full coat of poly.

Think would clean off the mess with acetone and get me a can of spray poly to use as finish. Good luck with it.

I too like lacquer over poly finishes but think poly better for something like a shaving brush or bottle stopper.

 

[JimB]

Just to add to my previous comments. I've never turned Wenge and didn't know it was an oily wood. In the past I have attempted to use WOP on some oily woods such as cocobolo without success. For those oily woods I do a CA finish. However, I don't have the experience or knowledge that JT has. Maybe if I did I would have success.

 

[Spinzwood]

After curing the oil poly.. should there be any problem adding coats of water based poly on top? I'm guessing not. I now have three coats of oil based on this and can still see pores that are chomping at the bit to be filled.

 

[Spinzwood]

Wildman Bill.. Someone else suggested the same thing. Strip and start over after a good wipe down with acetone.. I hope I don't have to resort to that. If that happens, I'l turn this one into a wine bottle stopper where I have no push to finish it.. and start a new one for the brush.

 

[jttheclockman]

After curing the oil poly.. should there be any problem adding coats of water based poly on top? I'm guessing not. I now have three coats of oil based on this and can still see pores that are chomping at the bit to be filled.

Again Bill I am voicing my opinion and my opinion alone. Others may have had different experiences and you can follow their suggestions.

You should have filled the pores before you top coated. Everytime you add more finish on top you just keep adding a deeper hole unless you sand back and use the poly as the filler.

Bill you should not mix products water with oil. Read the can about adding coats. If you let dry too long you have to wait longer than if you apply in a certain time slot. Many times they will say to sand or roughen up the prior coat if you wait too long. Instructions on the cans are for a reason and if you still have questions all products have web sites to check for further info.

If you started using oil and want to switch to waterbase you need to have the oil cured completely and that takes a long time. Usually shorter time in reverse but I never like that idea. The same thing goes for using oil stains and top coating with oil poly or vice versa. Mixing products is just not a good idea.

If anyone tells you to use steel wool please ignore. They sell woven pads that imitate steel wool and are made for wood. Steel wool is made for metals in today's market. Trust me on this.

 

[Spinzwood]

Thanks again, JT.. This confirms my doubt. I think I'll start a new one and lt this one cure for a bottle stopper after adding more poly. Now, in no hurry.

 

[Lucky2]

Isn't it quite possible, that putting it in the microwave could cause the wood to split? While your doing this to dry the finish, your causing the brass insert to expand and the wood to shrink. Even though the shrink and expansion of these two parts is minimal, it could be enough to cause the cracking. And now that think of it, the cracking could be caused by whatever you used to glue the parts together. There's all kinds of different reasons for blanks cracking, I don't think we will ever figure the reason out.

 

[Spinzwood]

Thanks, Lucky2. No inserts or glue/ca at the time I did do the 2 short bursts in the mW. This is a handle for a badger brush shaving accy. It did, however, do some fracturing along the grain lines as mentioned. Those voids were then filled with a bit of CA.

Appreciate taking the time to offer a suggestion.

Cheers, Bill

 

[jttheclockman]

Isn't it quite possible, that putting it in the microwave could cause the wood to split? While your doing this to dry the finish, your causing the brass insert to expand and the wood to shrink. Even though the shrink and expansion of these two parts is minimal, it could be enough to cause the cracking. And now that think of it, the cracking could be caused by whatever you used to glue the parts together. There's all kinds of different reasons for blanks cracking, I don't think we will ever figure the reason out.

Absolutely true. For what we do heat is never a good thing especially if it is forced. When people put pen blanks in an oven or microwave to get the moisture content down they can very easily introduce hairline cracks within that blank that may show up at any time latter on. Wood is slow dried. Finishes are slow dried.

 

[arkie]

On your top coat only, if it feels sticky but is cured enough not to "pill" when rubbed, you might try rubbing on a top coat of wax. I have had success solving that problem on other turned object that way.

 

[Spinzwood]

Thanks arkie, I may try that at a later time.