Tom The Sawyer
Portable Sawmill Service
K-10 & Evening Star Road Eudora, KS 66025
The purpose of the following information is to help you achieve the best quality lumber that your logs will yield. It is based on my personal experience. I certainly don't have all of the answers and I continue to learn as I gain experience and interact with other woodworkers and sawyers. There is a wealth of information available on the internet and you may find answers to specific questions or situations. Internet resources, even this one, are not infallible. Please ask questions.
The quality of your lumber starts with which logs are selected and how they are cut. Unless you have specific requirements for your lumber I would suggest cutting logs in increments of 2' (8', 10', 12', etc.) with an extra 3 or 4" added for trimming and squaring the ends. If I need 8' lumber I try to cut my logs at 8'4". It is much more efficient for drying purposes if you keep your log lengths consistent. Random lengths can be difficult to stack properly. If you have a 17' long log, you'll get more lumber if you cut it in half. It will also stack and dry more efficiently as 2 - 8' logs. Sometimes you don't have any choice, the log is what it is, and we'll get them milled up either way.
Consider sealing the ends of your logs to prevent degrade and checking as they dry. Wax-based products specifically made for that purpose (like AnchorSeal 2) are preferred but you could also use an exterior paint. Freshly cut ends will start drying almost immediately. Please do not use tar or roofing coatings which may damage the blade or stain your lumber. Also seal any areas where large branches were removed. If you are going to seal the ends it should be done before the log is milled. Sealing the ends of individual boards can be very time consuming. If it will be a month or more before your logs will be milled, try to get them off the ground. You can use landscape timbers, railroad ties, pipe or blocks. Decay and insect activity can start quickly. Logs do not need to 'season' before milling, they can not dry evenly while in log form. The outside will dry first, it will shrink and crack (check) while the inside of the log is still moist. I have milled logs that had been down for 15-20 years and sometimes they will still yield decent lumber, although the quantity will be less. Do not wait for logs to 'season', the sooner they are milled the better quality lumber you will get.
I have been air drying lumber for more than 25 years and it usually works quite well, if you are patient. Air drying has been used for thousands of years - and it will work for you. Prepare your air drying area before milling day - you'll be too busy that day. You will need spacing sticks (called "stickers") to separate the layers of boards. Stickers may be made of dry solid wood, plywood, or even composite materials. They should be at least as long as your stack is wide. They must reach completely across each layer of boards. Generally, it is better to build a taller stack rather than a wider stack - the concentration of weight helps keep boards on the lower layers flat. Most stacks are 3 or 4' wide. With a small quantity, like a single log, it may be better to use one board per layer.
Stickers should be 1/2" to 1" thick and about 1" wide. The size of the stickers can have an effect on how well your lumber dries by regulating the volume of air that can flow through the stack over a given time period. Stacking thick planks with thin stickers may not allow sufficient air flow to prevent mold. Using stickers too thick for the material being stacked can promote drying too rapidly and cause surface checking. An ideal location will permit air flow around the stack (don't stack against a wall) and yet prevent direct exposure to sun, rain, or snow.
How many stickers do you need? That depends on the total board feet you will be drying, the lengths and thicknesses of your lumber, along with the species. Each end of the boards should be supported and there should be stickers spaced equally for the length of the boards - usually from 12 to 24" apart. A stack of pine 2x10"s could be spaced every 24" while a stack of highly figured 4/4 walnut would probably do better spaced every 12". For most of my lumber I space at about 16" so a layer of 8' long boards would require 7 stickers. For example; if I needed to stack 500 board feet of lumber, a 3' deep layer of 4/4x8' boards would use about 23 bf per layer (allow a little for spaces). That means that it will take about 22 layers (always round up) for 500 board feet. At 7 stickers per layer that would be about 154 stickers. If some of the boards were milled thicker then there may be fewer layers but you should always mill enough of each thickness to complete a layer.
You will also need the same number of piers (base supports) as stickers per layer. In a dry area, on concrete I use 4x4s for my piers, on soil that is always dry perhaps 6x6s might work but if there is a chance the ground under the stack may get wet then the first layer should be at least 12" above the ground. Although the foundation may slope, it must be flat if you expect to get flat boards. Most pressure treated lumber has a high moisture content so if that is what you use, put a sticker on top of each 4x4 before the first layer of boards. When you stand back and look at the stack, the ends of the stickers should be in a vertical line above the piers. Top off the stack with additional stickers and some type of cover like plywood or barn metal. Any weight you can add to the top of the stack will help. Be very careful about covering the sides of the stack with anything that might impair the air flow.
I normally stack fresh cut lumber in an unheated area, outside or in a barn, until the moisture content level reaches less than 20%. Most of the potential for cupping, warping, and mold occurs above 20%. I may then move the lumber into my garage or basement and re-stack to complete the drying process. If you stack outside, and want to use some of it for a project, bring those boards is for a few weeks before you use them for indoor projects.
Note: Don't let a lack of stickers delay your milling project. I can supply plywood stickers in bundles of 25 upon a week's notice if you don't want to make your own. Current prices for 3' and 4' stickers are on the Sawmill Fees page.