Timing your Baking.

ian
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Timing your Baking.

Post by ian » Wed Nov 13, 2013 10:25 am

Hows it going lads!
I have a question for you.

How do you time your baking?
For example a powder that requires 10mins @ 200c.

A local powder coating company told me to place the coated items in the oven when it is at any temp.
When the oven (not part) reaches required temp (200c) start timing form there.
He used a system like this to time his bakes.

1mm = 3mins at requires temp.
2mm = 4mins
3mm = 5mins

I have read of people using a lazer to read the part temp, then when it reaches required temperature they start timing.

but what i cant understand is the local coating company dont actually check the part temperature and dont follow the powders guidelines (10mins @ 200c) unless its 7mm thick.

Any help would be great!

Thanks in advance :)

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Jay V
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Re: Timing your Baking.

Post by Jay V » Wed Nov 13, 2013 11:24 am

If I'm following you correctly - that's completely wrong.

You need to be able to read the part temp - oven temp isn't a good indicator.

Thin parts will heat up in minutes, thicker/heavier parts may take hours. No matter, you can't start your "cure time" until the part reaches the proper temp.

An IR temp gun is what most use to read the part temp.


Jay V
Last edited by Jay V on Wed Nov 13, 2013 12:26 pm, edited 1 time in total.

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redlinecoatings
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Timing your Baking.

Post by redlinecoatings » Wed Nov 13, 2013 11:25 am

That company doesn't have a clue what they are talking about. Cure temps are when the entire PART has reached the required temp. Then you would start the time. Most use IR guns and some use temp clips as well.

ed1966ss
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Re: Timing your Baking.

Post by ed1966ss » Wed Nov 13, 2013 11:28 am

There is a lot of mis-information out there. Eastwood has for years stated that the cure begins at flow out. I would believe what the manufacturers tell me. Here is a link to the NIC site that explains when to start the timer:

http://www.prismaticpowders.com/resourc ... estion/30/" onclick="window.open(this.href);return false;

Tiger Drylac has a chart that shows various cure durations based on substrate temperatures if you download their application data. Their durations are clearly stated based on substrate temperatures.

Other manufactures have basically the same information if you take the time to search. It sounds to me like your local coater is just too lazy to do it the right way and is just making generalizations about cure times.

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Re: Timing your Baking.

Post by Mike K » Wed Nov 13, 2013 4:49 pm

I was looking for a local over the counter supplier for powder. I rang the largest local supplier of paint and he said they don't stock powder but gave me the number of they local powder coating firm. I told the place I was looking at coating a few sets of wheels for me and some buddies - they said it would be cheaper to send to them! I said I already bough a gun. after that he wouldn't tell me a local supplier of powder as I would be taking work from them!! big place in a different town - you get me drift?

ian
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Re: Timing your Baking.

Post by ian » Wed Nov 13, 2013 6:10 pm

Thanks lads always a great help.
Nice piece of info ed1966ss, cheers.
Goodbody is my supplier in Dublin, Good service and they sell small amounts, could be posted to you in a day or two. They might even give you an number for a local uk supplier. Hope thats some help.

ian
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Re: Timing your Baking.

Post by ian » Wed Nov 13, 2013 6:21 pm

guessing that the oven would reach 200c before the part would?
So wait for the oven to reach 200c and then begin checking by slightly opining the door and hitting it with a infrared thermometer.
Can parts be over baked?

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redlinecoatings
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Timing your Baking.

Post by redlinecoatings » Wed Nov 13, 2013 7:00 pm

Yes. Depending on the part and your oven it could be over baked very easily. While a little over bake is nothing to worry about, getting it too far could cause issues with durability and with yellowing.

ed1966ss
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Re: Timing your Baking.

Post by ed1966ss » Wed Nov 13, 2013 8:35 pm

ian wrote:guessing that the oven would reach 200c before the part would?
So wait for the oven to reach 200c and then begin checking by slightly opining the door and hitting it with a infrared thermometer.
Can parts be over baked?
Go to the Tiger Drylac site and download one or two of their Product Date Sheets. Then look at the cure parameters chart and you will get a good idea about the range of temperatures that are acceptable. As an example, their Series 38 Super Durable powder cures at 200C for anywhere between 15-22 minutes. At 170C the acceptable time is 25-37 minutes.

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Re: Re: Timing your Baking.

Post by xtrememeasures10 » Thu Nov 14, 2013 8:50 pm

ian wrote:guessing that the oven would reach 200c before the part would?
So wait for the oven to reach 200c and then begin checking by slightly opining the door and hitting it with a infrared thermometer.
Can parts be over baked?
Yes the part will take longer than the oven to reach temp. An engine block can take and hour or more where as a thin piece of 24gauge sheet steel will nearly warm at the same rate as the oven. I would suggest you build a peep door in your oven as its a bad idea to open the entire door when the powder is in liquid state because it will cause dust and dirt to get pulled into the oven and stick to your part.

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