How to stop cracks - help!

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Forum topic by bues0022 posted 12-02-2011 06:38 PM 2912 views 1 time favorited 11 replies Add to Favorites Watch
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250 posts in 3304 days

12-02-2011 06:38 PM

Topic tags/keywords: question walnut maple

I’ve been working on a maloof-inspired rocking chair for almost a year now. The intent was to get it done before my wife had our first child…..which happened almost four months ago. Oh well. Because of the new baby I have worked on it only about 6 hours in 4 months – not a way to finish fast. BUT, maybe that’s good and bad. Bad because it’s slow going, but good because I’m uncovering problems and hopefully fixing them.

The seat pan for the chair is cracking. Background: Seat pan is laminated layers of spalted maple and walnut. The spalted maple had cracked prior to glue-up, but I put lateral pressure on it during gluing which closed the cracks. Now that it’s carved out and the seasons changing, it’s cracking pretty dramatically. I’ve been just filling the cracks with epoxy and since it’s spalted maple, am just going to chalk it up to “character” in the wood. My wife doesn’t mind the cracks and says “it’s how you tell it’s hand-made”. I’m not concerned structurally with the cracks, but am concerned about getting more cracks once I finally finish the chair. It will be quite difficult to patch a crack with epoxy and sand it down once it’s finished. SO, is there a way I can finish the chair with something that will penetrate the wood and harden it (clear) to keep it from cracking more? Do I just wait it out a bit and hope it cracks all it’s going to crack now – make the patches – and more forward? I know the “right” thing to do is to start over on the seat, but between being stubborn and not having any more spalted maple left, I’m going to keep trying to blast forward. Pics are below to show what I’m up against.

Thanks for any suggestions.

-- Ryan -- Bristow, VA

11 replies so far

View Jonathan's profile


2608 posts in 3194 days

#1 posted 12-02-2011 08:03 PM

I did a little research on this, and it seems like there are several products out there that will work well here. I have not tried any of these methods, so you should probably investigate a bit further before deciding if you want to use the suggestions. There is a product out there called Acraglas, which is used for bedding rifles. It is an epoxy of sorts, and you can mix fine spalted maple sawdust with it to really hide the cracks, in addition to filling them, and it should take most finishes as well.

You can also use CA glue in cracks, although the cracks you have might be a bit too large for that.

There appears to be some good information here:

Here’s some info. on Acraglas (the gel, which is newer than the original Acraglas):

Hopefully you’ll get some other responses here from people that have encountered a similar situation. Again, I have not tried any of the products mentioned in the links above.

Do you have any scrap cracked spalted maple that is from the same batch of wood, but not used for the chair? If you do, I’d experiment on that first. Good luck and keep us posted. That is going to be a beautiful rocker!

-- Jonathan, Denver, CO "Constructive criticism is welcome and valued as it gives me new perspectives and helps me to advance as a woodworker."

View Nomad62's profile


726 posts in 3102 days

#2 posted 12-02-2011 10:06 PM

Nice chair. The problem is that the spalted maple was wetter than the walnut, not to mention way softer; it really holds moisture. As the maple continues to dry, it will crack further as the walnut will hold solid and not shrink. The only way to get it to stop is to get it really dry, down to about 6% mc; probably not something a person wants to do once it has been glued up already. It is almost impossible to get any type of accurate mc reading on spalted wood without going thru a long, involved process using oven-baked test pieces and weighing the wetter stuff in comparison to the oven treated pieces as the spalted wood will not give out correct measurements on an electronic meter. It is one of the consequences of using a risky wood. The only thing I could guess at that may help would be to rub alcohol on the wood, it will tend to draw the water up and may speed the drying process further. I wish I had a better trick to give you, but it seems the road will still lead to doing nice fill-in work. It is worth it tho, that really does look nice.

-- Power tools put us ahead of the monkeys

View dbray45's profile


3320 posts in 2920 days

#3 posted 12-02-2011 10:17 PM

Agree with Nomad, you can do what you want, the spalted maple was compromised (that is what causes the spalting) from the start. It is a gamble using spalted woods with hardwood this way. Walnut tends to have a lot of stress and the maple is soft so they work like dissimular metals – it bends or breaks. Yours broke. Even if you dry it really well, the humidity will still be an issue – sorry.

Part of the learning process, I lost a nice piece of furniture that way. SInce then, I do not use spalted maple except as a veneer.

-- David in Damascus, MD

View bues0022's profile


250 posts in 3304 days

#4 posted 12-03-2011 05:26 AM

Well I guess it’s a good thing that I used a laminate instead of full thickness spalted maple! It’s still frustrated though. I attempted to dry it completely in an curing oven before flying, but it must have sucked up all that moisture from the glue. Combined with carving out the seat pan and relieving the stresses. I guess I’ll just hope that it stops moving soon, and epoxy it up like I’ve done before, and pry that it doesn’t happen anymore.

How about this follow-up question…...let’s say I epoxy it, finish, and a year later it cracks, how would I go about fixing the crack then after the finish is on?

-- Ryan -- Bristow, VA

View TopamaxSurvivor's profile


18373 posts in 3820 days

#5 posted 12-03-2011 09:06 AM

I have used the original Acraglas. It keeps rifle stocks stable. Not sure what it would do about cracks, but I would be willing to try it if it were me. The big risk I see is causing the cracks to move to another part of the seat when you stabilize one.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Nomad62's profile


726 posts in 3102 days

#6 posted 12-07-2011 06:25 PM

Using a piece of solid spalted maple could be less than desirable since it is quite soft to begin with… you might fall thru, lol. Maybe pretreating it with hardener would be a good idea next time…? You may consider using an epoxy finish, that way if it does crack again you could fill in the crack with the same epoxy to match. Try to be less discouraged, the only people that make errors are the ones that are doing something; anyone can set in a chair and be an expert. Live and learn, and thanx for sharing your less-than-fantastic situation for all of us to learn by.

-- Power tools put us ahead of the monkeys

View chrisstef's profile


17674 posts in 3150 days

#7 posted 12-07-2011 07:46 PM

I just used a product called Quikwood on a project to fill in much larger gaps and cracks. Worked like a charm. It doesnt take stain but they do make it in tinted colors and i would assumer that you could color it woth a dye. It sells at Woodcraft for about $7.50 a tube.

-- Its not a crack, its a casting imperfection.

View JamesVavra's profile


304 posts in 3460 days

#8 posted 12-08-2011 09:30 PM

There is a product sold for stabilizing punky turning blanks called polycryl. I have not used it (I generally like the random movement that occurs as my turnings dry out) but it might be just what you’re looking for:


View bues0022's profile


250 posts in 3304 days

#9 posted 12-08-2011 11:08 PM

I’ll look into the polycryl stuff. I’d probably try it on a separate chunk of wood first to see how it reacts with the epoxy that is filling the cracks. I also wonder how it finishes after it all dries out. (or if my wood would crack even more after rewetting/drying it yet again). Thoughts?

-- Ryan -- Bristow, VA

View bues0022's profile


250 posts in 3304 days

#10 posted 12-09-2011 05:49 AM

The product states the ability to use on spalted wood, but good point, what about spalted wood that has already been dried????

-- Ryan -- Bristow, VA

View cloakie1's profile


204 posts in 2699 days

#11 posted 12-09-2011 10:27 AM

trouble with dried timber that hasn’t got a finish on it is that it will take on moisture relative to humidity in the atmosphere….so it will constantly move….i would go with the epoxy and then try and get it sealed as quickly as possible….good luck

-- just get stuck in and have a go!!!

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