Archive for the ‘Projects’ Category

Corn Cob Blasting on a Budget

June 20th, 2009 36 comments

Log Siding corncob blasting2003 146We purchased a log sided home in 2003, not really knowing much about log care or treatment in general. I was less concerned about log siding than a log home, because the worse case is to remove the siding and replace it with new, if needed. I now have a better appreciation for the work that went into putting the siding in place. Log Siding corncob blasting2003 197

Our house was built in 1996. From what we can tell has had little to no care of the wood, since it was constructed. This has left the wood in a rough shape, having blackened and showing signs of wear and cracking after exposure to the elements. When approaching re-staining the house, we had the first challenge of removing the existing stain, and prepping the wood for new stain. You can’t really expect to hand sand an entire house of curved wood, so the typical approach is to use some chemicals combined with power washing to remove the stain. There are a few pieces that drove us away from that direction. We didn’t want to deal with chemicals, and masking off the ground and surrounding plant life around the house. We also learned that, depending on what chemicals you intend to use, you may need more chemicals to get the pH of the wood back to a level where it will accept the stain again.

The alternative out there was this process of blasting the stain off of the wood, using ground up corncob. Appreciate that nobody in the area of Rochester had a clue as to what we were talking about, and that perhaps 1 in every 10 people we talked to in the wood industry didn’t look at us cross eyed. Luckily there was enough information on the Internet to get us closer to understanding how to approach the process. Eventually we got in contact with Dick Alger at I Wood Care, who seemed to have the best grasp on the industry and approaching this project. I took a look at renting the equipment from I Wood Care and quickly discovered that this was not for the average home owner. Requiring nothing less than a compressor of biblical proportions, the nozzle system resembled something closer to the size of a fire hose. So I did what I always do, and decided I could build my own system for less money.

Poor Man’s Corncob Blasting

I decided to build my own system, using standard sand blasting equipment, because of the low investment it posed overall, figuring it was small Log Siding corncob blastingDSC07920risk to take in the investment to get the wood repaired. I bought a sand blaster from the mecca of cheap tools, Harbor Freight, and replaced the blast hose with a 30 foot extension. Then ordered what I considered to be a high CFM air compressor from Northern Tool, using points I had earned from my credit card and had a bag of corn shipped up from i Wood Care to give it a trial.

Log Siding corncob blastingDSC08027The system worked, but needed some refinement. Although the compressor was rated at 11.8 CFM At 90 PSI, it didn’t last for longer than a 15-20 seconds before dropping too low in pressure. I also neglected to account for this new thing Log Siding corncob blastingDSC07919called gravity. The further you get up that ladder the more pressure is required to move the blasting media, a progressively painful drop in usable air the higher you went up. I was very fortunate to have a friend at work who had a compressor that put mine to shame, and when I mentioned what I was trying to do, he let me borrow the setup for the months I would need to do the work. The project wouldn’t have happened if that did not fall into place.

The quotes we got from buying the actual bags of corncob were ridiculous. My wife ended up taking a day trip in the truck to go buy it from I Wood Care, because they were the only ones not looking to charge extortion rates for the media. We ended up ordering our stain and bug treatment from them as well.

You can re-use corncob a few times, if you are clever. We were not that ambitious, because we would usually be doing this project after work and did not have time to mess around with collection tarps, etc. Corn Cob Blasting Example

Choosing Stain and Bug Protection

Log Siding corncob blastingDSC08053Many different manufacturers of stain, and many different processes regarding bug treatment. For stain, we went with a stain that did not finish off with a polyurethane coat. Some log processes will take that direction, leaving that outer shell of protection in place. Every few years, you presumably give the polyurethane a re-coat and all is well. The negative is that if you miss the re-application and the stain below takes a toll, you need to figure out how to get stain back onto that wood. There were a lot of non-clear answers on this, all of which sounded like work. We opted to go with a stain that did not use a final protective coat, but could be re-applied as the years go on. Essentially every couple years we apply stain again. It sounds like work, but really we do one side every year, rotating around the house from year to year. The process takes less than an hour for us to re-coat one side, and it has worked out well so far.

You want to add some bug treatment to the wood, to discourage all of our bug loving friends from making a home in your house. Some of the treatments mix with the stain itself. The system we went with, which was Penetrete did not. It was was applied before the stain. The negative out of this, and perhaps something I would change given the choice to do it again, is needing to allow the bug treatment to setup over 12-24 hours. In upstate NY where ever other day is rain, this proved to be challenging. The best thing about corncob blasting is that the wood is cleaned, dry and ready for stain, which we lost with this process. Many a nights we scrambled to wrap the house in tarps, as we waited for the treatment to set in and crystallize over night.


What I learned and what I would offer for anybody approaching this from the same “do it yourself” perspective.

  • Find the largest air compressor you can find. Ideally you will want a construction grade trailer compressor that you would find on construction sites. I will not need to do our house again, but I still watch the classifieds to see if one comes around for a reasonable cost.
  • Get a sand blaster that has a large capacity, or is easy to fill. I wasted a lot of time refilling the corn into the blaster, because I had to go through a funnel. Stretch the budget $100 and get the large easy loading model. If not, consider getting two blasters, and have somebody loading the one, while you are blasting.
  • Keep the bags of corn dry. Consider keeping them someplace with a dehumidifier running. A little moisture made for more challenges getting the spray tweaked just right, than I care to admit.
  • The corn will get everywhere. Keep a set of clothes that you only where for this project and isolate then from the rest of the house, inside. That is about the best you can do.

I recently blasted the final logs, after some reconstruction work on our back wall. I took one HD video of the process itself, to show how nice the stain comes off.

It is amazing to see how the same stain applied to weathered and blackened wood appears, versus new cuts of wood. The house looks like a very dark color, but when applied to new wood, it appears very bright and light colored. If you need to replace one or two boards on a wall, you may be approaching replacing the entire wall, depending on how it affects the look of the house.

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