back prime T-111 with linseed oil mix?
johnnyd
| Posted in Construction Techniques on
I’m in the process of choosing a semi-transparent stain for ~ 1600 sq ft of 5/8″ T-111 siding, rotary cut SYP, 4″ OC grooves ($22.88 a sheet). Ben Moore and Cabot at least both offer tintable linseed-oil-based semi transparent product. Kind of pricey, but both seem highly recommended on this forum, as is back-priming any wood siding material.
Question is why not back prime with a straight 50/50 linseed oil-thinner mixture at about 1/2 or less the cost per sq ft? I’m thinking the expensive part of the tinted stains is the pigment/packaging/tinting/dealer profit etc…which I’m more than willing to pay….for the exposed side.
Any gottcha’s with this plan?
Replies
I am a big fan of boiled linseed oil. With boiled linseed, you need not cut it withsolvent, unless you are spraying it. Just role oon a coat or two and you are good to go.
My dad built a backboard for a basketball goal when I was 8 years old. We primed it with two coats of boiled linseed oil and then painted it with a 50/50 blend of linseed oil/paint. Less than a year later it was taken down when we moved. It was never put back up, and lay on the ground for the next twenty years with firewood stacked on it. When we finally tossed it out, it still had a lot of the original paint on it, and was amazzinly sound. The bottom course of fire wood was rotted, but that piece of 3/4 plywood and untreated 2x4s was still good enough to make shelving for the garage with. There was no such thing as treated lumber in 1955 when he built it. Of course it was probably lead paint also :).
Dave
Straight linseed oil takes forever to dry. Maybe that's not an issue.
The 75 year old owner of the last real paint store here says to cut it with turp, not mineral spirits. I never question what he tells me...I just do it.
I have a DIY recipe for exterior stain provided by the above guy (BM dealer). I can hunt it up if you want to save some $$ on the side that shows.
Yeah, I've always cut it 50/50, and it still takes awhile to dry.
No thanks on the DIY brew...DW is pretty particular about the exact color of the stain and I'll need local coaching and mixology from my BM dealer here.
Thanks for the offer though.
Linseed doesn't dry. It cures by reaction with oxygen. There is a difference. That is why the dealer recommended turpentine instead of modern mineral spirits. It kicks off the same. Spirits of turpentine was developed to be more volatile and evaporate quicker. Then they started making it from oil instead oif from the turpentine tree.
the cheapest way to get something like this for backpriming is to pick up discontinued gallons. I get the olympic stuff discontinued for about 3-4 bucks a gallon. It has some pigment and is already cut enough for good penetration of the wood.
I like backpriming too but don't know if I see a need in this case. is it a shed or a heated house? are you applying the t11 directly to studs or over other sheathing? plywood products already have a VB built in in the glue.
If you do backprime with cheaper sealer of any sort, you will want to do the faces first and then backprime in this case or the sealer that weeps around at edges will try to stop the finish stain from taking evenly.
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This siding goes on a heated residence in SE MN. It is sheathed with OSB and layered with TYPAR.
I've used T-111 before as combo sheathing/siding directly to the studs and never backprimed, with good results. Maybe there's something to that: If T-111 is NOT backprimed and attached directly to the studs, it has a way of drying to the inside. Do you think I will be risking locking moisture in the wood fibers by applying back-primed T-111 directly over TYPAR'd sheathing?
I just seem to get the overwhelming message from numerous posters here that you should always back-prime. I'm just trying to find a less expensive material to accomplish this.
If you do backprime with cheaper sealer of any sort, you will want to do the faces first and then backprime in this case or the sealer that weeps around at edges will try to stop the finish stain from taking evenly.
This is what I was thinking about this morning...which order. Makes sense to do the face first, including edges, let it dry, then backprime.
In your case, It won't hurt anything to backprime.
there are two main reasons for backpriming.
One is to prevent the wood from absorbing moisture on the back and either rotting or cupping. Your ply panels won't cupp but it can't hurt to stop moisture I suppose.
The other is to prevent that moisture from making the paint peel off as it boils out through. You are using semi stain so that won't happen anyway.
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Thanks for your input.
So you don't think I'd be considered a Hack if I just lay it up raw without back prime?
Not in this case.
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you can add japan drier to your BLO to speed up oxidation. Paint stores sell Japan drier, can be used with any oil based product. Read the instructions and MOST certainly properly dispose of rags that contained oil based products mixed with japan drier.
I agree with the admonition to take great care with the rags. It is not dynamite but a couple of rags rolled up can get forgotten until the firemen point them out for you. Stored in a bucket of water, a sealed fire rated can or laid out or hung flat, this allows them to dry and remain cool.
Had a neighbor who had a fire. A very small pile of rags, he was painting pictures not a house, caused a big fire.
Hey, I would love that recipe, always looking for cheap old-timer solutions, and any that involve linseed oil are ok by me
Here you go Rick...
3 parts boiled linseed oil
1 part turp
1 part Armor-All Water Repellent. Also acts a solvent to drive the oil mix into the wood
1 part BM Deck and Siding Stain Clear #07600. Got linseed, solvent, transparent amber pigment, mildew inhibitors
1 part BM Moorwood Solid Oil Stain. Optional for color. In this quantity you wind up with transparent. Also has an ultra-violet inhibitor.
I've used this several times. Just like the store bought for a lot less $$.
ShelleyinNM
thanks, looks good!
I recomended boiled linseed oil. It is a thinner than regular linseed oil, and the oxidation process is faster.
Piffen is correct about the drying process. Many oil based paint are made from soya oils (soy beans), and even flax oils. Drying time for any of these oil bases is dependent on the lenght of the oil molecule. Short oils dry faster than long oils. but the trade off is in film flexibility. Short oils tend to be brittle and long oils more flexible.
The addtion of a dryer is a good idea.
I don't know much about the solvent line up, so I would likely do a test batch to test the oils tolerance to high levels of a particular solvent. He can tell when the solvent threshold is reached by watching the clarity of the blend. If it starts to get cloudy or gets stringy, he is near the point of what we use to call "kick out". Time to stop when you reach that point, or the oil is ruined. It either turns into a gel or a bucket of snot, and aften can't be rcovered by adding more oil.
Dave
>> ... and even flax oils.
Flax oil is linseed oil.
My bad.
I was trying to remember way back to the early 70s. I think we may have even formulated with sun flower seed oil. We tried some wierd stuff durring the Nixon wage and price freeze era. Could have even been under the Ford administration and the begining of the oil embargo/ Iran hostage period. Everyone was scrambling to do "profit improvement projects." Between those and the birth of the EPA, and California's Rule 66, the whole paint industry was pretty much fubar'ed.
Dave
Flax seed and lin seed are one and the same, under differing names
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