High temp mortar

If I make my own high temp mortar, is the lime the same as the lime powder you use on your lawn? Also, if I were to buy the 50 lb bag of Heat Stop (dry), how many bags would I need? This is for the smaller Matone (Barille).
Thanks for a quick response!!

Welcome to the BrickWood forums, Dana!

Here’s the spec on the lime:

Hydrated Lime / Powdered Lime / Construction Lime -

This is the product that confuses some of our customers. It is NOT granulated Lime that is sold in the plant section at Home Depot or Lowes but a white and fluffy material that looks and feels like powdered sugar. It is used in the masonry and landscape industry – but it also used in the Plant Nursery industry in 50lb bags.

If you are unable to find this product at your Landscape Supply, call a local Plant Nursery and they can order lime for you.

Here is the link to the full article.

Thanks for the reply, can you tell me how many lbs if I use the Heat Stop dry mix mortar?

I don’t have the instructions for the Mattone Barile handy, but here is a link to a post that will tell you exactly how to figure it out. (And I promise it’s easy, because I wrote it to be easy for ME! :slight_smile: ) Just look in the instructions for your oven to find out how much TOTAL mix is recommended, and then go to this post:

Figuring out your ratios

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Don’t use Castable Cement in lieu of Fireclay. You need a DRY FIRECLAY to make the mortar. Castable Cement is not the right product -

Thx for asking first before mixing!

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I want to make the high temp mortar mix 3:1:1:1.

This is what the masonry store stated will work as fire clay. Is this ok to use?

From what I’ve read a lot of people have used the H.C. Muddox clay successfully. It’s even shown on the Brickwood materials picture gallery elsewhere on this site so I think you’re all set.

I’ve read on some sites that they suggest you can go outside and dig your own clay if you know what you’re looking for. I’d stick with the bags though…

BTW. Welcome to the forum.



Thanks for your response. The bag of HC Muddox I saw on the picture gallery had (ceramic material) written on it but can’t find anyone who sales it. I will take your advise and use the one in the above picture. Thanks for your help.