OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Paint and Decals PAINT HELP - Best Way to Prepare Before Painting

Hi,

I am rebuilding a 1987 Briggs and Stratton engine (on an Edger). The engine was covered in oil and dirt when I took possession of it, as it hadn't been used for about 10 years. I have cleaned the majority of the parts using some Autoglym degreaser, but I am not sure if I should be doing anything else before painting.

Does anyone have any recommendations on the best way for degreasing and preparing the surface for painting?




Thanks,
Cain

Hi cosullivan there are many different ways to remove paint one of the best ways would be to sandblast,but you wouldn't do the engine that way.Like most people (me included) don't have a sandblaster.So then to get get somebody to do then cost money.Maybe more than it would be worth.
So you need to find the best way for you to do it.Like for what I can see most the paint still seems to be in reasonable condition.So for that I would just use somewhere from 100grit to 400grit sandpaper just to scuff the surface,giving the new paint something to stick to.Or if you wanted to go deeper you could use paint stripper,however that can get messy.For the steel parts I use a Technic called electrolysis,it's brilliant will remove all the paint and even rust.It will only work with steel no alloy.For your case I'd just use sandpaper no setting up and no real mess at the end,may take a little longer.For the engine and head I'd just use a wire bush on a drill.As I said you'd have to work out what is best for you.
I hope that helps.

Hi Cosullivan,
HAve to agree with blumbly. electrolysis is great for removing the rust, and won't hurt the steel either. Lifts the rust that canbe under paint. Also, I use a small -about 2 inch - slightly conical shaped wire brush in the drill press to shift the dirt and paint and rust from parts. Works a treat, but need to be careful using the brush on flat mating surfaces in case you score the alloy.

Recently took the engine and flywheel to the carwash and used their engine cleaning soaker stuff. Let it sit for a couplel of minutes and then used the high pressure soap. Got the majority of gunk off, but I still needed to scrape a bit when I got it home. I found a piece of hard plastic was handy for scraping without scratching. The final stages a needed fine emery to clean the fins on the flywheel.

Hope this helps. Oh, I have also just painted my finished bits with spray on primer/undercoat as used for car painting, and will be using VHT brand heat resistant enamel for finish coats. Seems to be a bit tougher than normal enamel. And I will finish everything with a couple of coats of VHT spray clear enamel.

Jeff49

After all this time I am yet to paint an engine, my first will be done over the next couple of weeks, a villiers whic hI bought as a box of parts I will finally reassemble.

Anyhow, I am planning on pressure washing the parts to be painted, wire brushing the hell out of it and hitting any paint thats left with wet and dry to smooth it all out.

I havent built my electolisis setup yet, I did scab an old chest freezer to seal up and use as a tub to hold the water though. I figure with something that big I can clean just about any mower part!

I couldnt find the green I wanted in the paint range so I got some bright red 300 degree enamel. not sure what everyones painting technique is but I will elaborate further later on with pics in my own thread.

Hi Cosullivan,

You can also use Sodium Hydroxide(NaOH) to strip paint in minutes. This is available in supermarkets and hardware stores as drain cleaning powder and costs about seven bucks for a 500g container. The trick is to use hot water and agitation. Ideally in an old esky, fill it with hot water and then add about half of the powder to make your solution, then very carefully submerse your painted parts into the mix (best done with tongs or a piece of wire tied around them) and let the chemistry do it's work. Please note, NaOH is extremely corrosive (no 8) to skin and deserves a lot of respect. That said, it will remove decades old paint in a second without harming ferrous metal. I have been using this method for years with great results, just be sure to use PPE and common sense.

p.s. don't get any alloy parts near NaOH, it will destroy them.

Craig

[Censored] Mark_x11 that sounds very harsh and a little bit dangerous.What do you do with the liquid after that.Doesn't sound safe to pop it into a drain?I think I'll stick with the electrolysis may take a bit longer,but it's not as scary.Would like to know a little bit more about it though.Could be handy if I'm in a hurry to remove paint.So how much water to how much Sodium Hydroxide? Also does it produce fumes?

Hi Blumbly, if you re-read Marks preamble, you will see that Sodium Hydroxide is drain cleaner. You can safely put it down any drain after you have cleaned your parts.
As with working with any chemicals, you must wear protective clothing, goggles etc.and use common sense.

Sounds like something I think I will give it a try.Shame it can't be done on alloy.

Is Sodium Hydroxide a close relative of caustic soda? I can understand the need for precautions - caustic soda can do a lot of damage to tissue.

Used to dissolve alfoil in caustic, in a home made pressure vessel, pass the gas through a couple of water filters, and use the gas (hydrogen)to inflate balloons. Then send the balloons off into the wild blue yonder. All when I was 15, mind you. Had a few nasty burns from exploding pressure vessels.

Yes, sodium hydroxide (NaOH) is the correct technical name for caustic soda.

Take this one seriously: do not mess with this stuff without wearing safety glasses.

You can tell whether you are dealing with pure NaOH if you touch it with your bare fingers: it feels slippery, because it is dissolving your skin so fast that it forms a slippery layer between the two surfaces.

I regard pure caustic soda as too dangerous a substance to keep in the house, despite warning labels etc. Furthermore it is likely to damage nearby materials. Yes, rather strong caustic is sold as a drain cleaner unfortunately. In the old days you used to be able to buy arsenic, cyanide, and strychnine too. Better sense prevailed with those other substances, but not yet with NaOH. Hopefully, the system will improve eventually.

I definitely agree with your sentiments there, grumpy...It's a bit like cigarettes; the only product probably in the world that proclaims on the pack...If you use this product, it can kill you!!

Sounds like something I'm happy to stay away from.

yeah, yeah, yeah....the bottom line is that it works.....