Learn Plastic Bumper Repair Vid 3/5: Apply Primer

appliedcolors.c...
TRANSCRIPT:
We want to avoid getting primer where it isn't needed because it creats a lot of sanding work for us. So we'll mask off the area where we've sanded this bumper. But we're going to use a technique called 'back taping' with our masking tape. And it works like this. I'll apply my tape and paper like this, then fold it backwards. And what that does is creates what's called a soft tape line. That measn that when I spray primer here there won't be any 'hard' tape lines. And we want to avoid hard tape lines because they take a long time to sand out. [robert back tapes the primer area]
[primer, scale, and cup on table]
The primer has a mix ration of 2 parts primer to 2 parts activator to 1 part reducer. In a typical bumper corner repair you don't need any more than 1.5 ounces of primer.
Our scale measures in grams. An ounce is about 28 grams. so we want to mix about 40 total grams of primer. So if we use 8 ounces as our base number, we're looking to mix 2 parts of oprimer, therefore 16 ounces of primer. now we're mixing 2 parts of activator, and that too will be 16 ounces of activator. finally, 1 part reducer will be 8 ounces.
so let's turn on our scale, let it set itself to zero and pour out our primer, activator, and reducer.
Stir it up and it's ready tod spray.
[robert holding spray gun]
Before I spray anything I do two things. First I make sure the pressure regulator is at 28 lbs with the trigger open.
Second, I like to spray a little thinner through the gun just to make sure the gun is clean and has a healthy fan patter [robert sprays thinner through the gun].
So let's drop a strainer over our cup and fill it up with the primer.
[the bumper]
Apply 2 or 3 medium coats. Watch my hand speed and note how thickly I lay the thinner
[spray the bumper]
[spray gun over refuse can]
Now let's dump our unused primer into a refuse can. I'll wash out the cup with some thinner and dump that into the can. Now I'll fill up the cup with enough thinner that the thinner pushes the primer out of the nozzle. When the thinner flows freely I'll dump the thinner into the refuse, pull the trigger to release the last amount of fluid in the cup and wipe it dry with a towel.
[the bumper]
It's been about 15 minutes and the primer is set up and ready to sand. Libewrally apply water and sand with 600 grit until smooth.
[robert sands the panel, then dries with towels].

[@emid7976]

Be careful with that cup, it's made of paper with wax. Don't want ending with wax into your paint.

[@Wardropulous]

Whoever did the original paint job seems to have got quite a bit of dripping toward the underside of the bumper. Thought it was the primer at first, but it wad there before you started spraying.

[@Teqo7]

this man knows his shit

[@zaftra]

Great tip with that back liner.

[@josephdisandro9483]

To much work for a small repair. Why all the mixes and the scale? Where is a can of plastic putty and hardener?

[@bayliss2399]

How come you primed over shiny paint

[@MM2009]

not flashed enough between coats of primer

[@smileyrod11]

what kine of gun your using let me know thank

[@eddiecard]

what kind of primer ?

[@catsoandahalf]

Good info, thanks for the vids!