Tech Questions - Preparation of Steel Surfaces
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- What kind of primer should I use on steel surfaces?
- What if zinc chromate is already on the surface?
- How should I clean the surface prior to applying the epoxy primer?
- How soon after bead blasting should I apply the primer?
- Should I wipe the surface down with any chemical prior to applying the primer?
- How do I mix epoxy primer?
- What about thinning the primer?
- Can I brush the primer on?
- How many coats should I spray on?
- After mixing, how long do I have to spray the primer before it begins to cure?
- How long before the primer dries?
- How much coverage will I get with 1 gallon of primer?
- What do I use to clean my spray gun?
- Are there any health hazards involved in spraying epoxies?
- How long can I store the primer?
What kind of primer should I use on steel surfaces?
Use only epoxy primers. The cements and dopes you will be using with the covering process do not affect these two-part primers.
What if zinc chromate is already on the surface?
Usually you can simply spray epoxy primer over any existing one-part material without any problem. It will then have the proper protection.
How should I clean the surface prior to applying the epoxy primer?
You must remove all old fabric, cement, rust, etc. from the surface prior to applying the primer. An effective method of doing this is to bead blast the area. Care must be taken, however, not to use too much pressure that could damage the tubing.
How soon after bead blasting should I apply the primer?
Immediately upon completion of the blasting. If steel parts remain in open air without protection they will begin to rust within just a couple of hours. You should have the primer and spray gun ready before you begin the blasting operation.
Should I wipe the surface down with any chemical prior to applying the primer?
Yes, wipe all bare areas down using Poly-Fiber's C-2200 Metal Surface Cleaner. This will remove all oil, grease, and any contaminants that will adversely affect the primer. Wipe dry using a clean rag-not a shop rag that may contain chemicals.
How do I mix epoxy primer?
Mix our epoxy primer as follows: Add exactly 1 part of the EP 430 catalyst to 2 parts of the EP-420 base chemical. Stir thoroughly and allow to sit 30 minutes prior to application. This allows time for the needed chemical reaction to take place.
What about thinning the primer?
We recommend thinning for spray gun application. Use only E-500 epoxy reducer and add about 50% by volume to the primer.
Can I brush the primer on?
Yes, but it may not have a pleasing appearance. Spraying is recommended.
How many coats should I spray on?
Spray a light "tack" coat on 1st and allow it to dry for a few minutes. Then apply 1 full coat. Allow to dry about 10-15 minutes and then apply another coat. On steel tubing it is advisable to spray on an additional coat simply because it is difficult to completely cover a steel tube structure. In other words, it is easy to miss areas.
After mixing, how long do I have to spray the primer before it begins to cure?
This time is known as the "pot-life" of a paint. The pot life of catalyzed primer is about 7 hours. Once the thickening occurs, you should discard the remaining primer.
How long before the primer dries?
It will dry to the touch in about 1 hour. Full cure to develop resistance to solvents will take about 7 days.
How much coverage will I get with 1 gallon of primer?
A 1 gallon kit will actually produce approximately 2 gallons of primer. This will cover about 1000 square feet.
What do I use to clean my spray gun?
Use E-500 reducer to clean the gun.
Are there any health hazards involved in spraying epoxies?
Care must be taken when handling epoxies. You should protect your hands and avoid all skin contact. Use a charcoal-filtered respirator when spraying.
How long can I store the primer?
On the shelf, unopened, it will last about 4 years from the date of manufacture.