A little more on Straw!

[G.T.]

Hi to all! The application of color, from straw to peacock blue can be accomplished in several different ways. But in reality, probably comes down to three ways to do it properly. The first way isn't really planned, it's just the color is dictated by the degree of heat treating the part is subject to when made, this is very visiable on commercial hold open latches where they have a rainbow of colors! That process is probably pretty hard to repeat by us, as we are not doing a 100 or 1000 pieces at a time! Quantity, has an affect on the outcome same as heat and time, different results when any of the variables are altered.

The second way is in a hot liquid salt solution, same as fire blue, only different heat, and most likely different time. I have experimented with this method, and although it yields nice results, it is labor intensive, and you've got the added liability of a hot salt liquid just waiting to burn you! But, it is a method to an end, and can be used with some trial and error.

The third way, and most common to most of us is the oven method. Now most have had some success just heating to oven to 450 and tossing in the parts and low and behold, they're yellow, or sorta yellow, mostly yellow except for that purple spot, or brown gold spot.. you catch my drift on this.

But the reason I'm writing this is to give all you shade tree Luger smiths with a household oven a fighting chance, here's what you need to do, and why you need to do it.

Getting a correct straw or wheat (light straw) finish to turn out correctly requires that you do some, "improvements" to your heating source, yup, the kitchen oven and here is why. A normal oven has exposed elements, top and bottom. They glow red to orange hot, when they are preheating, I'm not sure how hot, but 1K degrees F wouldn't be a surprise to me! They are giving off radiant heat which means they are well over 450 degrees next to the element, and way less in the middle of the oven. So, the first step is to reign in the elements! On the top rack, just put a large cookie sheet. but on the bottom rack, I put in an, upside down, large, (giant) cast iron frying pan! At this time, I also set a regular tin foil pie pan on the cast iron pan, as when we are finished with the strawing process we can pluck it out easily with a pliers or some such tool. So now we've blocked the radiant heat energy and are utilizing convection heating, which I guess uses the air heated by both the elements and metal objects to get to the 450 that our straw effort requires. The last step in or heat source prep is simply patience? I set the temp to 450 and forget about it for an hour or two. When I return, everything in that oven is now 450!! We now have some controlable consistency in our project!!! So, on top of the frying pan, Into the pie pan, I quickly toss in my part(s) lets say just the ejector, each part is different, and each oven is different, but different parts require different times. I let it soak for 3 minutes, and then quickly extract the pie pan from the oven, quickly closing the door to hold in the heat, as does our cast iron frying pan. You have to do the same process for each part, or groups of parts. Probably allow 10 to 15 minutes between attempts. If you don't like the results, repolish and re try, with a different time setting, more or less to get your desired results!

There! Now you know everything I know, go forth and fight the gallent battle of small parts strawing! Best to all, til.....lat'r....GT

[reiver]

Great Info GT...can you cook a meal at the same time

[G.T.]

Only if you can make the egg stay on the upside down pan! Best, til....lat'r....GT...

[mrerick]

Made this a sticky.

Some more background. This first link is for stainless steel:

https://bssa.org.uk/bssa_articles/he...heated-in-air/

These articles discusse "tempering" steel in general:

https://knifemaking.com/pages/forgin...at-color-chart

https://sheffieldgaugeplate.co.uk/bl...-colour-chart/

https://en.wikipedia.org/wiki/Tempering_(metallurgy)

And another article on tempering steel, in this case a lunch box:

https://www.instructables.com/Home-O...eringColoring/

[ithacaartist]

G.T.

I've devised a toaster oven method for strawing. It takes some dialing in initially, but once the proper setting is established, a mark on the temperature dial will take you to right to it next time around. The correct temp seems to be in the low 400s F.

The problem that can arise with using a higher temperature than necessary is that it's possible to over-temp the thin portions in order to get the thicker parts to take on the correct color. I use a small vessel containing sandblasting sand, which is pre-heated for about 45 minutes to get it to the precise temp, after which I immerse the parts in the sand and let 'em "soak" for a half hour or so. You could leave them in the oven overnight and they would still come out the same, no watching, no guesswork.

If you have a powerful enough toaster oven, it's possible to achieve the other colors such as the blue, as well.

[G.T.]

Hi David! Excellent info and yet another excellent method to combat the heat Gods! Thanks for sharing... best to you, til.....lat'r...GT