A good consistent investment is crucial, We QC ours twice prior to packaging. However reaction layer is controllable. Time & temperature are key...you can use special investments if you can't control your time & temperature well. The decision is yours, however they tend to be expensive and totally unnecessary.
99% time I find that no one realizes how significantly out of calibration their burnout ovens are and how much affect they have on their pressing results. If you would all switch labs for one day and use each others equipment, you would find out how different your results are using identical materials.
It amazes me when I walk into a laboratory that complains of inconsistencies and I measure their burnout ovens, how far off they are. I don't mean 5 or 10 degrees F, I am seeing fluctuations between 50-150F! You have no idea how many times I have seen this. Even laboratories with a calibration protocol have a lack of real understanding the ovens and their effects.
Everyone is looking at the investment or adding something to the investment, or this or that or...the list goes on. The funny thing is... it's as simple as time & temperature. Usually it has to do mostly with your burnout!
1.
temperature (too high - more reaction layer & even surface issues) / (Too Low - mis-presses)
2. Different investments have different thermal masses, one investment will work better for you than another because of the way you are set up. Hot ovens or cold, plunger type used (Alox or disposable),practice consistencies..
Most burnout ovens are cheap, the parts are cheap, but the problems are expensive.
1. Thermocouples in burnout ovens are exposed to a lot of contamination and therefore should be closely monitored.
2. Heating elements in burnout ovens usually gather toward the bottom of the oven or fall over with detached insulation linings, they should be replaced.
3. People overload their ovens often...buy another oven or slow down.
4. Place your rings so that they see the elements on all/both sides of the rings evenly, this will help control overloading and make sure rings are not under heated.
5. Keep them at least 1 inch from the elements and back of the oven and at least 1.5" to 2" from the front of the oven.
6. Make sure your burnout oven is at the FINAL hold temperature for speed cycles before you put a ring in the oven or start the timer for the ring.
All of these points are important, not to say there are not other factors, but I promise you, if you really scrutinize your burnout...you will see a difference quickly.
