Info needed: Soda blasting versus Paint Stripper

[Robin Craig]

Good day,

I wanted to post this here and not in my vehicle thread as it is of general interest.

One of the body tubs on my CL70 is near being ready for paint removal.

As I see it, I can buy paint stripper and do it myself or send it out and pay for soda blasting, which I have been told is best for aluminum items. The tub is a composite structure with riveted components added.

I am concerned that if I use stripper it will wick in behind the laminations and bleed back out again at the primer / paint stage.

Some how I would prefer the stripper avenue as I can do it myself, pride and satisfaction in a task and hopefully lower cost, I am trying to be frugal and also make progress.

Can anyone give some comments please?

Thanks

[Matthew P]

Maybe not the answer you are looking for;

What if you use a wire brush in a grinder or drill for the areas near rivets and seams, then use stripper for the larger panel surfaces?

Matt

[chris vickery]

Robin, typically with most strippers it is advisable to rinse and neutralize with
water one done but kind of defeats the purpose especially on ferrous items.
Have you considered wet blasting that is now available?
It uses a combination of high pressure water and sand.
Aluminum can be successfully stripped using fine grain sand and lower pressure application.

[Lynn Eades]

The "sand" blaster guy told me that they have all kinds of trouble trying to get paint to stick to what the "soda" blaster guy blasted.
I don't know if that's bluff or if there is truth in it.

[Andrew Rowe]

I noticed the other day a guy soda blasting an aeroplane, so obliviously there
must be an etch prime that will stick on alloy. Typically when sandblasting you are looking for a 25 micron "pitting" (surface ) for the paint to adhere to. If you use coarser media , like garnet or steel grit you will get a deeper micron finish, before painting.

[sth65pac]

Originally Posted by Andrew Rowe

I noticed the other day a guy soda blasting an aeroplane, so obliviously there
must be an etch prime that will stick on alloy. Typically when sandblasting you are looking for a 25 micron "pitting" (surface ) for the paint to adhere to. If you use coarser media , like garnet or steel grit you will get a deeper micron finish, before painting.

Yes, there is a paint that sticks to aluminium or ten.

With aircraft you need to use compatible paints not just anything or your plane turns into white powder. Most common up until recently was a form of zinc chromate, the greenish yellow paint you see in many aircraft. The chromate has been omitted these days and a two pack type paint is used. (this is a short version)

Soda blasting could be detrimental to aluminium, and you may find that the person undertaking the task was using plastic media which is commonly used on aircraft as it leaves no residue or creates a dielectric mixture. It also does not create areas of stress on the alloys - another bad thing with aircraft.

Also you need to be meticulous when using paint strippers on aluminium as many will cause entitlement (material loses its strength).

I have never used soda blasting as it does not remove rust, only paint. If you want to strip back a vehicle without damaging the metal then soda is the preferred method. The risk is the if you don't get it all out, you basically have a huge battery and the rate of corrosion will be massive.

in short: soda takes off paint but not rust. 'Sand' blasting removes rust and paint, stripper removes paint but may leave reside.

cheers,

Ian

[Robin Craig]

Thank you all for some very technical and useful information that I need to digest a bit.

I think one of the problems that the vehicle had during it's construction is that unlike other aluminum fabrications that I have been involved with, there was no scuffing process of any kind prior to paint from what we can see.

I have been around flat sheeting machines in sheet metal shops and random orbital sanders. The material I am working with is silky smooth, so I think I am going to first get a plain old pressure washer and see how much more some water can remove before I do anything else and maybe I will have a lot less work to do.

I did buy a gallon of aircraft paint remover at an advantageous price but I am going to hold off a bit yet.

more later

[Phil Waterman]

Originally Posted by Robin Craig

Thank you all for some very technical and useful information that I need to digest a bit. ......

I have been around flat sheeting machines in sheet metal shops and random orbital sanders. . The material I am working with is silky smooth, so I think I am going to first get a plain old pressure washer and see how much more some water can remove before I do anything else and maybe I will have a lot less work to do.

I did buy a gallon of aircraft paint remover at an advantageous price but I am going to hold off a bit yet.

more later

Hi Robin

Couple of thoughts, before you try the "aircraft paint remover" I"ve had very good luck removing OD paint with White Wall Cleaner like Purple Power, and a pressure washer and hot water. If your paint is flattened it may work nice and it leaves a smoother finish than the "aircraft paint remover" .

The Purple Power or like cleaner seems to soften the paint and the preasure washer strips it. Have also found that the Purple Power works well when used as a liquid when wet sanding with low speed orbital sander.

Using warm water while sanding or pressure washing improves the stripping effiecey.

I've got some photos of the effectiveness of cleaner vs paint stripper that I will post later to day.

Could you take some pictures to share of your project before during and after paint removal?

Cheers Phil

Here are the photos I was talking about, one on the left is paint stripper at 15 minutes, 30 minutes, and 24 hours as you can see longer time doesn't really improve stripping. Right photo is cleaning the HUP rear hatch with just cleaner and hot water. Paint was 20 year old Dupont Delux Enamel, paint came off basically one layer at a time till down to the primer.

[45jim]

As your vehicle has construction materials and elements closely associated with aircraft perhaps you should look to that group for advice. It seems that you can certainly remove the paint with soda but you must then clean thoroughly, etch and then apply aluminum conversion coating of chromic acid. Then you can prime and paint in the usual way.

http://eaaforums.org/showthread.php?...Aircraft-Paint