I have a handbuilt log home from the 70’s that has black tar / mastic chinking (Black Jack?). Logs are a poorly scribed Swedish cope, so the gap is small 1-2”. A mortar chink intrigues me (serious DIY), especially cost savings over synthetic. Logs are very stable, haven’t seen any movement or history marks of settling. Is my gap too small for mortar. And will future buyers be put-off by mortar chinking? Thanks!
Using mortar is a waste of time and money. When the mortar dries it will pull away from the logs and allow water to get in behind anyway. You are better off leaving as is. And yes, mortar chinking will turn off potential buyers. If you are going to use any thing, use Energy Seal. A little pricey I know, but will add value to the home and will put up with the movement of the logs. DO NOT try to save money and use some box store caulk either. It too will fail over time and be expensive to remove. Call Dave at 800-564-2987 for help.